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© 2018 J. J. Crabtree | www.jonathancrabtree.com
2
In 300 BCE the Greek Euclid of Alexandria
defined multiplication as repeated addition.
a to the power of b (ab) equals a into itself b times.
a into b (a × b ) equals a added to itself b times.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
3
Zero is defined as a – a
‘a number subtracted from itself’.
The Arabic world embraced India’s
ideas on Zero and negative numbers.
Arabic maths was then adopted by Leonardo Pisano
who brought India’s ideas on Zero to Europe.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
4
© 2018 J. J. Crabtree | www.jonathancrabtree.com
5
Your ‘facts’ are false!
Everyone is entitled to their own opinion, yet not to their own facts.
Extraordinary Claims
Require
Extraordinary Evidence
© 2018 J. J. Crabtree | www.jonathancrabtree.com
6
✔
•India’s definition of ZERO never made it to
either the ancient Arabic world or Europe.
© 2018 J. J. Crabtree | www.jonathancrabtree.com 7
•In the Arabic world, India’s ZERO only
came to exist as a placeholder, not as the
power tool to solve simple problems like
+3 minus +4, or –2 minus –4, or –4 minus +2
Extraordinary Claims
Extraordinary Evidence...
Al-Khwārizmī (c. 780-850)
“So they made 9 symbols, which are
these: 9 8 7 6 5 4 3 2 1.
...
Because one is the root of all number
and is outside number. It is the root
of number because every number is
found by it.
...
But it [one] is outside number
because it is found by itself, I mean,
without any other number.”
© 2018 J. J. Crabtree | www.jonathancrabtree.com 8
Al-Uqlīdisī (c. 920-980)
“Why is zero multiplied by zero equal to zero
and zero multiplied by any letter zero?
We say that by multiplying zero by zero the
aim is only to occupy the place; the same
applies for multiplying the letter by zero.
We multiply the letter by zero ... to occupy
the place, and tell that there is a place and
that it is empty.
© 2018 J. J. Crabtree | www.jonathancrabtree.com 9
200 years after Brahmagupta,
al-Khwārizmī did not accept 1 as a
number. Zero as a number? Never!
© 2018 J. J. Crabtree | www.jonathancrabtree.com 10
300 years after Brahmagupta,
al-Uqlīdisī accepted India’s ZERO as a
placeholder, yet not a number. Why?
© 2018 J. J. Crabtree | www.jonathancrabtree.com 11
Al-Uqlīdisī means ‘the Euclidist’. He
was known for his skill in studying
the Greek geometry of Euclid and
translating it into Arabic.
Around 300 BCE, Euclid defined ‘number’ as a
multitude of units. So Euclid’s definition of
number came before 0 and 1 were numbers.
© 2018 J. J. Crabtree | www.jonathancrabtree.com 12
As we will see, India defined zero as the sum of
opposing negative and positive numbers with
the same multitude or magnitude.
If Arabic and European writers in medieval times
really understood India’s zero, where are all the
negative numbers in their writings?
© 2018 J. J. Crabtree | www.jonathancrabtree.com 13
“I have read a few dozen medieval Arabic books on arithmetic
and algebra, and there is no hint of negative numbers in any
of them. Zero, too, was not regarded to be a number, but was
merely the place holder for an empty place in the
representation of a number in Arabic (Indian) notation.”
“All numbers in Arabic arithmetic were positive. No Arabic
author to my knowledge ever even contemplated the existence
of negative numbers.”
By email courtesy of Dr. Jeffrey Oaks, Professor of Mathematics on:
Medieval Arabic algebra and the mathematics of Greece and medieval Europe
© 2018 J. J. Crabtree | www.jonathancrabtree.com 14
© 2018 J. J. Crabtree | www.jonathancrabtree.com 15
© 2018 J. J. Crabtree | www.jonathancrabtree.com 16
Back to the future...
© 2018 J. J. Crabtree | www.jonathancrabtree.com 17
18
19
Images courtesy of
the British Library.
For this talk,
Brahmagupta’s
Laws of Positives
Negatives and
Zero have been
freshly analysed.
20© 2018 J. J. Crabtree | www.jonathancrabtree.com
21© 2018 J. J. Crabtree | www.jonathancrabtree.com
22© 2018 J. J. Crabtree | www.jonathancrabtree.com
Brahmagupta’s 5
Addition Laws
AL
(saṅkalana)
© 2018 J. J. Crabtree | www.jonathancrabtree.com 23
positive plus positive is positive
AL1
© 2018 J. J. Crabtree | www.jonathancrabtree.com 24
negative plus negative is negative
AL2
© 2018 J. J. Crabtree | www.jonathancrabtree.com 25
positive plus negative is the difference
between the positive and the negative
AL3
© 2018 J. J. Crabtree | www.jonathancrabtree.com 26
when positive and negative
are equal the sum is…
AL4
© 2018 J. J. Crabtree | www.jonathancrabtree.com 27
ZERO
AL4
© 2018 J. J. Crabtree | www.jonathancrabtree.com 28
when positive and negative
are equal the sum is…
“…sunya (ZERO) is neither
positive nor negative
but forms the boundary line
between the two kinds,
being the sum of two equal
but opposite quantities.”
Joseph, G. G. (2016). Indian mathematics:
Engaging with the world, from ancient to modern
times. World Scientific. p. 208
29© 2018 J. J. Crabtree | www.jonathancrabtree.com
positive plus zero is positive
AL5 part 1
© 2018 J. J. Crabtree | www.jonathancrabtree.com 30
negative plus zero is negative
AL5 part 2
© 2018 J. J. Crabtree | www.jonathancrabtree.com 31
zero plus zero is zero
AL5 part 3
© 2018 J. J. Crabtree | www.jonathancrabtree.com 32
positive plus zero is positive
negative plus zero is negative
AL5
zero plus zero is zero
© 2018 J. J. Crabtree | www.jonathancrabtree.com 33
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Brahmagupta’s 5 Addition Laws
positive plus positive is positiveAL1
negative plus negative is negativeAL2
positive plus negative is the difference between the
positive and negativeAL3
when positive and negative are equal the sum is zeroAL4
positive plus zero is positive
negative plus zero is negative
zero plus zero is zero
AL5
34
Following text from: Plofker, K. (2009).
Mathematics in India: 500 BCE-1800 CE. p.
151, Princeton, N.J: Princeton University Press.
Brahmagupta’s 5
Subtraction Laws
SL
(vyavakalana).
35© 2018 J. J. Crabtree | www.jonathancrabtree.com
[If] a smaller [positive] is to be
subtracted from a larger positive,
[the result] is positive.
SL1
© 2018 J. J. Crabtree | www.jonathancrabtree.com 36
[If] a smaller negative (is
subtracted) from a larger negative,
[the result] is negative.
SL2
© 2018 J. J. Crabtree | www.jonathancrabtree.com 37
[If] a larger [negative or positive is to be
subtracted] from a smaller [negative or
positive, the algebraic sign of] their
difference is reversed - negative
[becomes] positive and positive negative.
SL3
© 2018 J. J. Crabtree | www.jonathancrabtree.com 38
A negative minus zero is negative, a positive
[minus zero] positive; zero [minus zero] is zero.
SL4
© 2018 J. J. Crabtree | www.jonathancrabtree.com 39
When a positive is to be subtracted from a
negative or a negative from a positive, then
it is to be added.
SL5
© 2018 J. J. Crabtree | www.jonathancrabtree.com 40
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Brahmagupta’s 5 Subtraction Laws
A smaller positive subtracted from a larger positive is positive.SL1
A smaller negative subtracted from a larger negative is negative.SL2
If a larger negative or positive is to be subtracted from a smaller
negative or positive, the sign of their difference is reversed –
negative becomes positive and positive negative.
SL3
A negative minus zero is negative,
a positive minus zero is positive,
zero minus zero is zero.
SL4
When a positive is to be subtracted from a negative
or a negative from a positive, then it is to be added.SL5
41
Seeing is Believing!
Applying Brahmagupta’s
5 Addition Laws
AL
© 2018 J. J. Crabtree | www.jonathancrabtree.com 42
– negative + positive© 2018 J. J. Crabtree | www.jonathancrabtree.com 43
AL1
positive plus positive is positive
© 2018 J. J. Crabtree | www.jonathancrabtree.com 44
AL2
negative plus negative is negative
© 2018 J. J. Crabtree | www.jonathancrabtree.com 45
positive plus negative is the difference
AL3
© 2018 J. J. Crabtree | www.jonathancrabtree.com 46
3 holes
7 bumps
Podo the Puppy by
AFX Animation
© 2018 J. J. Crabtree | www.jonathancrabtree.com
3 negatives
7 positives
Podo the Puppy by
AFX Animation
© 2018 J. J. Crabtree | www.jonathancrabtree.com
3 negatives
7 positives
Podo the Puppy by
AFX Animation
© 2018 J. J. Crabtree | www.jonathancrabtree.com
So –3 + +7 = +4
3 holes (–3) and 7 bumps (+7 )
leads to 4 bumps (+4 )
Watch the AFX Animation
video of Podo the Puppy
squaring a circle with rope!
© 2018 J. J. Crabtree | www.jonathancrabtree.com
ZERO
ZERO
when positive and negative are equal the sum is ZEROAL4
© 2018 J. J. Crabtree | www.jonathancrabtree.com 51
plus ZERO
AL5
positive
plus ZERO
negative
© 2018 J. J. Crabtree | www.jonathancrabtree.com
ZERO + positive = positive, ZERO + negative = negative, ZERO + ZERO = ZERO
is positive
is negative
52
Seeing is Believing!
Applying Brahmagupta’s
5 Subtraction Laws
SL
© 2018 J. J. Crabtree | www.jonathancrabtree.com 53
If a smaller positive is subtracted from a
larger positive the result is positive.
SL1
larger positive minus smaller positive is positive
© 2018 J. J. Crabtree | www.jonathancrabtree.com 54
If a smaller negative is subtracted from a
larger negative the result is negative.
SL2
larger negative minus smaller negative is negative
© 2018 J. J. Crabtree | www.jonathancrabtree.com 55
If a larger positive is to be subtracted from a
smaller positive, the sign of their difference is
reversed – positive becomes negative.
SL3
We don’t have enough positives. So use AL4 and AL5.
3 positives minus 4 positives?
© 2018 J. J. Crabtree | www.jonathancrabtree.com 56
If a larger positive is to be subtracted from
a smaller positive… e.g. positive 3 – positive 4
SL3
AL4 “when positive and negative are equal the sum is zero”
AL5 “positive with zero is positive”
minus
Add ZERO
© 2018 J. J. Crabtree | www.jonathancrabtree.com 57
SL3
Add ZERO
Subtractminus
© 2018 J. J. Crabtree | www.jonathancrabtree.com
AL4 “when positive and negative are equal the sum is zero”
AL5 “positive with zero is positive”
58
If a larger positive is to be subtracted from
a smaller positive… e.g. positive 3 – positive 4
SL3
Add ZERO
Subtract
Simplify
© 2018 J. J. Crabtree | www.jonathancrabtree.com
AL4 “when positive and negative are equal the sum is zero”
AL5 “positive with zero is positive”
59
If a larger positive is to be subtracted from
a smaller positive… e.g. positive 3 – positive 4
SL3
Add ZERO
Subtract
Simplify
© 2018 J. J. Crabtree | www.jonathancrabtree.com
AL4 “when positive and negative are equal the sum is zero”
AL5 “positive with zero is positive”
60
If a larger positive is to be subtracted from
a smaller positive… e.g. positive 3 – positive 4
SL3
Add ZERO
Subtract
Simplify
© 2018 J. J. Crabtree | www.jonathancrabtree.com
AL4 “when positive and negative are equal the sum is zero”
AL5 “positive with zero is positive”
61
If a larger positive is to be subtracted from
a smaller positive… e.g. positive 3 – positive 4
If a larger positive is to be subtracted from
a smaller positive, the sign of their difference is
reversed – positive becomes negative.
SL3
3 positives minus 4 positives is 1 negative
© 2018 J. J. Crabtree | www.jonathancrabtree.com 62
If a larger negative is to be subtracted from
a smaller negative, the sign of their difference is
reversed – negative becomes positive.
SL3
We don’t have enough negatives. So use AL4 and AL5.
2 negatives minus 4 negatives?
© 2018 J. J. Crabtree | www.jonathancrabtree.com 63
If a larger negative is to be subtracted from
a smaller negative… e.g. negative 2 – negative 4SL3
AL4 “when positive and negative are equal the sum is zero”
AL5 “negative with zero is negative”
minus
Add ZERO
© 2018 J. J. Crabtree | www.jonathancrabtree.com 64
SL3
AL4 “when positive and negative are equal the sum is zero”
AL5 “negative with zero is negative”
Add ZERO
Subtractminus
© 2018 J. J. Crabtree | www.jonathancrabtree.com 65
If a larger negative is to be subtracted from
a smaller negative… e.g. negative 2 – negative 4
SL3
AL4 “when positive and negative are equal the sum is zero”
AL5 “negative with zero is negative”
Add ZERO
Subtract
Simplify
© 2018 J. J. Crabtree | www.jonathancrabtree.com 66
If a larger negative is to be subtracted from
a smaller negative… e.g. negative 2 – negative 4
SL3
AL4 “when positive and negative are equal the sum is zero”
AL5 “negative with zero is negative”
Add ZERO
Subtract
Simplify
© 2018 J. J. Crabtree | www.jonathancrabtree.com 67
If a larger negative is to be subtracted from
a smaller negative… e.g. negative 2 – negative 4
SL3
AL4 “when positive and negative are equal the sum is zero”
AL5 “negative with zero is negative”
Add ZERO
Subtract
Simplify
© 2018 J. J. Crabtree | www.jonathancrabtree.com 68
If a larger negative is to be subtracted from
a smaller negative… e.g. negative 2 – negative 4
If a larger negative is to be subtracted from a
smaller negative… the sign of their difference is
reversed – negative becomes positive.
SL3
2 negatives minus 4 negatives is 2 positives
© 2018 J. J. Crabtree | www.jonathancrabtree.com 69
negative minus zero is negative
SL4
4– minus 0– is 4–
positive minus zero is positive
zero minus zero is zero
3+ minus 0+ is 3+
© 2018 J. J. Crabtree | www.jonathancrabtree.com 70
When a positive is to be subtracted from a
negative … then it is to be added. –4 – +2
SL5
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Add ZERO
–4 – +2 = ?
71
When a positive is to be subtracted from a
negative … then it is to be added. –4 – +2
SL5
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Add ZERO
Subtract
–4 – +2 = ?
72
When a positive is to be subtracted from a
negative … then it is to be added. –4 – +2
SL5
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Add ZERO
Subtract
–4 – +2 = –6
For you. Show how a negative
subtracted from a positive
is to be added with +3 – –5
73
Brahmagupta’s 4
Multiplication Laws
ML
(guṇana)
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Text from: Plofker, K. (2009). Mathematics in India
74
ML1
The product of a negative
and a positive is negative
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Brahmagupta multiplies positives and negatives by either
adding to zero multiple times or subtracting from zero multiple times.
–a × +b
–a added to zero b times
75
False from 1570: a into b, (a × b), is a added to itself b times
Negative Multiplicand Multiplied by Positive Multiplier
–a × +b
–a added to zero b times
×
added to zero times
Next, from pictures to equations…
–2 × +3
–2 added to zero 3 times
76© 2018 J. J. Crabtree | www.jonathancrabtree.com
Negative Multiplicand Multiplied by Positive Multiplier
–2 × +3 = –2 × (0 + 1 + 1 + 1)
–2 × +3 = 0 + –2 + –2 + –2
–2 × +3 = 0 + –6
–2 × +3 = –6
–a × +b
–a added to zero b times
–2 × +3
–2 added to zero 3 times
77© 2018 J. J. Crabtree | www.jonathancrabtree.com
Positive Integer Multiplied by Negative Multiplier
+2 × –3
Brahmagupta did not say “The product of a positive and a negative
is negative”. However, we can demonstrate this via his Laws.
+a × –b
+a subtracted from zero b times
78© 2018 J. J. Crabtree | www.jonathancrabtree.com
Positive Multiplicand Multiplied by Negative Multiplier
×
+a × –b
+2 subtracted from zero 3 times
+2 × –3
As we don’t have any positive
twos to subtract, we first add
zero in the form +6 + –6
79© 2018 J. J. Crabtree | www.jonathancrabtree.com
Positive Multiplicand Multiplied by Negative Multiplier
×
Next, from pictures to equations…
+a × –b
+2 subtracted from zero 3 times
+2 × –3
80© 2018 J. J. Crabtree | www.jonathancrabtree.com
Positive Integer Multiplied by Negative Multiplier
+2 × –3
+2 × –3 = +2 × (0 – +1 – +1 – +1)
+2 × –3 = 0 – +2 – +2 – +2
+2 × –3 = 0 – +6
+2 × –3 = –6 + +6 – +6
+2 × –3 = –6 + 0
+2 × –3 = –6
81© 2018 J. J. Crabtree | www.jonathancrabtree.com
ML2
The product of two
negatives is positive
© 2018 J. J. Crabtree | www.jonathancrabtree.com
–1 × –1 = +1
A demonstration goes like this…
Crabtree,JonathanJ.Snippet:Anew
reasonnegativemultipliedbynegativeis
positiveVinculum,Vol.52,No.3,Jul2015:
82
ML2
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Negative Multiplicand Multiplied
by Negative Multiplier
–a × –b
–a subtracted from zero b times
–1 × –1
–1 subtracted from zero 1 times
83
Brahmagupta Defined ZERO in Law AL4
when positive and negative are equal the sum is ZERO
© 2018 J. J. Crabtree | www.jonathancrabtree.com
–1 × –1
84
–1 subtracted
from zero 1 times
+ –1+1
Brahmagupta Defined ZERO in Law AL4
when positive and negative are equal the sum is ZERO
+ –1
© 2018 J. J. Crabtree | www.jonathancrabtree.com
–1 × –1
–1 subtracted
from zero 1 times
now prove it equals +1
∴ –1 × –1 = +1
85
+1
ML3 The product of two
positives is positive
© 2018 J. J. Crabtree | www.jonathancrabtree.com
ML4 The product:
- of zero and a negative,
- of zero and a positive,
- or of two zeros
is zero.
86
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Brahmagupta’s 4 Multiplication Laws
The product of a negative and a positive is negative.ML1
The product of two negatives is positive.ML2
The product of two positives is positive.ML3
The product of zero and a negative,
of zero and a positive, or
of two zeros is zero.
ML4
87
MY ASSESSMENT OF THE WORLD’S
PEDAGOGICAL EVOLUTION (628 to Now)
© 2018 J. J. Crabtree | www.jonathancrabtree.com 88
Brahmagupta’s 4
[Non-Zero]
Division Laws
DL
(haraṇa)
© 2018 J. J. Crabtree | www.jonathancrabtree.com 89
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Brahmagupta’s 4 Division Laws
A positive divided by a positive is positive.DL1
A negative divided by a negative is positive.DL2
A positive divided by a negative is negative.DL3
A negative divided by a positive is negative.DL4
90
NOTE: Why Non-Zero Division Laws Only?
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Whilst zero divided by any non-zero number (0/±n),
is zero, Brahmagupta says a non-zero number
divided by zero(i.e. ±n/0), remains ‘zero divided’.
Commentators such as Bhāskara II (1114 –1185)
suggested n/0 is infinite or indeterminate.
91
© 2018 J. J. Crabtree | www.jonathancrabtree.com
MODELS OF DIVISION
Partitive Model Equal Groups
+12 ÷ +4
Q. If you have 12 things and 4 equal
groups, how many things go in each group?
A. 3 things go in each group.
12 ÷ 4 = 3 things
Partitive Model ✔
92
© 2018 J. J. Crabtree | www.jonathancrabtree.com
MODELS OF DIVISION
Quotitive Model Repeated Subtraction
Q. If you have 12 things, how many times
can you subtract 4 things?
A. You can subtract 4 things
3 times until you get 0 things.
12 ÷ 4 = 3 times
Partitive Model ✔
Quotitive Model ✔
+12 ÷ +4
93
© 2018 J. J. Crabtree | www.jonathancrabtree.com
METHODS OF DIVISION
Equal Groups
Repeated Subtraction
Equal Groups
Equal Groups
Repeated Subtraction
Equal Groups
Repeated Subtraction
Repeated Subtraction
✔
✔
✔
✔
✘
✘
✘
✘
94
© 2018 J. J. Crabtree | www.jonathancrabtree.com
MODELS OF DIVISION
Partitive Model Equal Groups
+12 ÷ –4
Q. If you have 12 positive things and negative 4
groups, how many things go in each group?
A. You can’t have a negative
number of groups!
Equal Groups ✘
Model Fails
95
© 2018 J. J. Crabtree | www.jonathancrabtree.com
MODELS OF DIVISION
Quotitive Model Repeated Subtraction
Q. If you have 12 positive things, how many
times can you take away 4 negative things?
A. You can’t subtract 4 negative
things from positive things. Try...
+12 – –4 = +16, – –4 = +20, – –4 = +24. i.e.
You go the wrong way and never get to zero.
+12 ÷ –4
Equal Groups✘
Repeated Subtraction✘
96
Model Fails
© 2018 J. J. Crabtree | www.jonathancrabtree.com
PROPORTIONAL COVARIATION, PCV
Equal Groups✘
Repeated Subtraction✘
Numbers are counts or measures
of standard units. We choose 1.
All numbers are measured by
the unit called 1.
1 is the multiplicative identity
and the divisional identity.
97
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Equal Groups✘
Repeated Subtraction✘
Our goal is to convert
12/4 into the form n/1
DENOMINATOR
To make –4 be +1 we take one of
the 4 parts of –4, which is –1 and
subtract it from zero to get +1.
PROPORTIONAL COVARIATION, PCV
98
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Whatever we have done to the
denominator, we must do to the
numerator to keep the number (ratio)
NUMERATOR
We take one of the 4 parts of
+12, which is +3 and subtract it
from zero to get –3.
PROPORTIONAL COVARIATION, PCV
Equal Groups✘
Repeated Subtraction✘
99
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Whatever we have done to the
denominator, we must do to the
numerator to keep the number (ratio)
PROPORTIONAL COVARIATION, PCV
Equal Groups✘
Repeated Subtraction✘
100
(Zero Minus Numerator) by
(Zero Minus Denominator)
–12
+4
Multiplication:
Whatever we do to the Unit 1 to make the Multiplier b
we do to the Multiplicand a to make the Product c.
Division:
Whatever we do to the Divisor b to make the Unit 1
we do to the Dividend a to make the Quotient c.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
PROPORTIONAL COVARIATION, PCV
101
As –4 is to +1 +12 is to...
102© 2018 J. J. Crabtree | www.jonathancrabtree.com
© 2018 J. J. Crabtree | www.jonathancrabtree.com
3 MODELS OF DIVISION
Equal Groups
Repeated Subtraction
Proportional Covariation Proportional Covariation
Proportional Covariation
Equal Groups
Repeated Subtraction✔
✔
✔
✔
✔
✔
103
Proportional Covariation ✔
+12 ÷ –4
✔
PROPORTIONAL COVARIATION, PCV
104
–2 x –3 = ? (i.e. negative two subtracted three times from zero)
What do we do to the standard Unit 1 to
make the Multiplier –3?
We place three Units and subtract them
from zero to make the Multiplier –3.
PROPORTIONAL COVARIATION, PCV
105© 2018 J. J. Crabtree | www.jonathancrabtree.com
–2 x –3 = ? (i.e. negative two subtracted three times from zero)
PROPORTIONAL COVARIATION, PCV
What do we do to the Multiplicand –2
to make the Product ?
We place three Multiplicands and
subtract
them from zero to make the Product +6.
106© 2018 J. J. Crabtree | www.jonathancrabtree.com
+2 –3 ?
+2 × –3 = ?
a × b = ?
We start off with
+1 in this square
Then we put b the
Multiplier here
+2 × –3 = ?
a × b = ?
We start off with
+1 in this square
+2 –3 ?
+2 –3 ?
Then we put a the
Multiplicand here
+2 × –3 = ?
a × b = ?
Then we put b the
Multiplier here
We start off with
+1 in this square
To go from +1 to –3 we
took 3 Units & changed
their sign by subtracting
from 0.
So, we take 3 a’s and
change their sign by
subtracting from 0 to
make c.
+2 × –3 = ?
a × b = ?
Then we put b the
Multiplier here
We start off with
+1 in this square
+2 –3 ?
Then we put a the
Multiplicand here
+2 × –3 = ?
a × b = ?
+2 –3 ?
+2 × –3 = ?
a × b = ?
+2 –3 ?
+2 × –3 = ?
a × b = ?
+2 –3 ?
+2 –3 ?
+2 × –3 = ?
a × b = ?
+2 × –3 = ?
a × b = ?
+2 –3 ?
+2 × –3 = ?
a × b = ?
+2 –3 ?
PCVMultiMat
PCVDiviMat
117© 2018 J. J. Crabtree | www.jonathancrabtree.com
–2 x –3
As +1 is to –3 so –2 is to +6
PROPORTIONAL COVARIATION PCV
b
a
c
1
118© 2018 J. J. Crabtree | www.jonathancrabtree.com
René Descartes
1596 – 1650
Brahmagupta
598 – 668
Brahmagupta’s ideas were not applied 1000 years later, yet should have been.
Copyright © 2016 Jonathan Crabtree All Rights Reserved
“For example, let AB be taken as unity, (1), and let it be required to
multiply BD (the multiplicand) by BC (the multiplier), I have only to join
the points A and C, and draw DE parallel to AC; and BE is the product
of this Multiplication.”
Applying Indian Logic to Descartes’s Multiplication
https://www.geogebra.org/m/wprjkwam
Let point B be 0 and line segments on the other side of 0 be negative...
https://www.geogebra.org/m/wprjkwam
A Negative Multiplicand and a Negative Multiplier result in a Positive Product.
https://www.geogebra.org/m/je3SEyQr
www.geogebra.org/m/ZBTZd6AF
www.geogebra.org/m/v62CqVEN
© 2018 J. J. Crabtree | www.jonathancrabtree.com 125
www.bit.ly/New-x-Model
Q. Why no numbers
in Greek Geometry?
A. Aristotle
Greek Philosopher
384–322 BCE
Geometry cannot be
proven with arithmetic
© 2018 J. J. Crabtree | All Rights Reserved
www.jonathancrabtree.com
Discussion on Brahmagupta’s Laws
© 2018 J. J. Crabtree | www.jonathancrabtree.com
A. Even though the numbers are different, both
numerators are smaller than their denominators.
Q. How can the following fractions be equal?
+
1
+
2
=
+
4
+
8
127
Discussion on Brahmagupta’s Laws
If one side has a smaller number on the top and the other side
has a larger number on the top, even if the same numbers
are used as before, the two sides can’t be equal.
+
1
+
2
≠
+
8
+
4
© 2018 J. J. Crabtree | www.jonathancrabtree.com 128
Discussion on Brahmagupta’s Laws
Q. Is the following equation correct?
+
1
+
2
=
−
4
−
8
© 2018 J. J. Crabtree | www.jonathancrabtree.com
A. Yes. Therefore, just as +1 < +2 we must accept –4 < – 8, to be
consistent with Brahmagupta’s laws and the laws of proportion.
The British system has –4 > – 8, which is illogical given positives
and negatives are equal and opposite. Brahmagupta’s laws
of integer ordering are intuitive logical and correct!
129
Discussion on Brahmagupta’s Laws
The same number of positives and negatives
sum to zero as they are equal and opposite.
Therefore today’s integer inequality laws, based
on Greek foundations 1000 years older than India’s
are out-of-date and sub-optimal.
© 2018 J. J. Crabtree | www.jonathancrabtree.com 130
Which numbers are greater?
or
or
or
or
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Discussion on Brahmagupta’s Laws
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Which numbers are greater?
or
or
or
or
x x
x xxx xxxx xx
xxxx x xxx
xx xx xxxxx x
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Discussion on Brahmagupta’s Laws
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Which numbers are greater?
or
or
or
or
xx xx x x
xx xx x xxx
x x
xx xx x xxx xx
5+ < 7–
9+ > 4–
1+ < 3–
5+ ≹ 5–
xx xx
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Discussion on Brahmagupta’s Laws
© 2018 J. J. Crabtree | www.jonathancrabtree.com
© 2018 J. J. Crabtree | www.jonathancrabtree.com
1+< 3+ 1–< 3– 2–= 2– 3–>1+ 3+>1–
1–< 3+ 1+< 3– 2+= 2+ 3–>1– 3+>1+
2+ 2–o=2+ are equal and opposite to 2–
134
…to multiply a by integral b is to add a to itself b times
Collins Dictionary of Mathematics
© 2018 J. J. Crabtree | www.jonathancrabtree.com
In book VII, Euclid defines multiplication as ‘when that which is
multiplied is added to itself as many times as there are units in the other’
The Development of Multiplicative Reasoning
in the Learning of Mathematics
1 × 1 = 2?
© 2018 J. J. Crabtree | www.jonathancrabtree.com
136
Paper @ www.bit.ly/LostLogicOfMath
Returning India’s zero reveals unseen patterns.
a × +4 = 0 + a + a + a + a
a × +3 = 0 + a + a + a
a × +2 = 0 + a + a
a × +1 = 0 + a
a × 0 = 0
a × –1 = 0 – a
a × –2 = 0 – a – a
a × –3 = 0 – a – a – a
a × –4 = 0 – a – a – a – a
Integral multiplication involves
either repeated addition or repeated
subtraction of the multiplicand from
zero, depending on the sign of the
multiplier.
137© 2018 J. J. Crabtree | www.jonathancrabtree.com
The Billingsley ‘virus’of 1570 (BV1570) spread widely! CLICK HERE FOR MORE
When explaining a3, Sir Isaac Newton used the Latin word ‘bis’,
meaning ‘twice’, so a3 is a twice into itself. Yet because of Henry
Billingsley’s mistranslation of Euclid’s definition of multiplication, upon
translating from Newton’s Latin into English, the translator changed
Newton’s explanation.
To match Billingsley’s approach, (thought to be Euclid’s), Newton now
reads ‘… the Number 3 in the Quantity a3bb, does not denote that bb is to
be taken thrice, but that a is to be thrice multiplied by itself.’ So, today,
we find, nonsense definitions of exponentiation that simply do not work!
© 2018 J. J. Crabtree | www.jonathancrabtree.com© 2018 J. J. Crabtree | www.jonathancrabtree.com
© 2018 J. J. Crabtree | www.jonathancrabtree.com
23 ≠ 16
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Cube ‘the result of multiplying a number,
quantity, or expression by itself three times’.
Collins Dictionary of Mathematics
If a3 is a into itself three times, we get the sequence
a into a, into a, into a.
If 23 is 2 into itself three times, we get the sequence
2 into 2, into 2, into 2, which is 16.
Just as India’s 0 went missing from definitions of multiplication,
we now know 1 went missing from definitions of exponentiation!
Returning the identity element one into exponentiation.
a+4 = 1 × a × a × a × a
a+3 = 1 × a × a × a
a+2 = 1 × a × a
a+1 = 1 × a
a 0 = 1
a–1 = 1 ÷ a
a–2 = 1 ÷ a ÷ a
a–3 = 1 ÷ a ÷ a ÷ a
a–4 = 1 ÷ a ÷ a ÷ a ÷ a
Integral exponentiation involves either
repeated multiplication or repeated
division of the base from one,
depending on the sign of the exponent.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
140
a+b = 1 into a, b times
2+3 = 1 into 2, 3 times, 1 × 2 × 2 × 2
a–b = 1 by a, b times
2–3 = 1 by 2, 3 times, 1 ÷ 2 ÷ 2 ÷ 2
There is much confusion about cubes and cube roots. CLICK HERE FOR MORE
South
West
Left
Down
Debts
Loss
Deaths
Emigration
Cold
Decay
Below Zero
Less Than Enough
Below Ground
To the hour
Deceleration
Head Wind (knots)
Under Par (golf)
North
East
Right
Up
Assets
Profit
Births
Immigration
Hot
Growth
Above Zero
More Than Enough
Above Ground
Past the hour
Acceleration
Tail Wind (knots)
Over Par (golf)
Counts or measures
of negative units
Counts or measures
of positive units
Simple Symmetries of Quantity
©2018J.J.Crabtree|www.jonathancrabtree.com
141
© 2018 J. J. Crabtree | www.jonathancrabtree.com
It has been said…
“God created the universe from
nothing, from Shunya, from Zero”
Planet Positron
Planet Negatron
Wherever opposing quantities or forces are equal you will find zero.
142
It’s as if ZERO was split, creating
infinite real number lines from ZERO.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
• China had positives and negatives in the 2nd Century BCE,
yet their first maths text with India’s zero, (with a symbol 0)
came in 1247 CE in The Mathematical Treatise in Nine
Sections, by Qin Jiushao.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Discussion on Brahmagupta’s Laws
• China used positives and negatives in their mathematics for
about1400 years without any concept of a number zero.
• The Chinese did not define negatives as less than zero. Their
positives and negatives were simply equal and opposite,
consistent with science and the philosophy of Yin and Yang.
144
Is zero defined as ‘a number subtracted from itself’ (n – n)?
No. Brahmagupta AL4 says zero is the sum of equal positive and
negative quantities. Zero is defined by addition, (–n + +n) not
subtraction, for use with Indian Laws of positives negatives and zero.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
145
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Are lessons on inequalities correct? e.g. (–4 > –7)
No. SL3 says if a larger negative is subtracted from a smaller negative
the sign of the difference is reversed and negative becomes positive.
We prove – 4 > –7 false by contradiction. Assume –4 > –7 true. We
subtract larger from smaller as –7 – –4 and the difference is –3. As the
sign of the difference is NOT reversed we cannot assume –4 > –7 true.
Thus –4 < –7 as seems obvious. (A debt of ₹400 is less than a debt of
₹700.) Brahmagupta’s SL3 also holds for greater positive from smaller
positive as +4 – +7 = –3 and the sign is reversed as SL3 states.
146
Are negative numbers ‘less than zero’?
No. Numbers represent count or measures of quantities, even abstract
units. The big bang created matter and antimatter. Equal in magnitude,
electrons have negative charge and positrons have positive charge.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
When antimatter and matter meet, they annihilate each other, producing
energy. It is said “God made the Integers”. Those integers are consistent
with physics. NOTE asymmetry between matter versus antimatter in universe = Baryon asymmetry
“If God made the Integers, when it comes to fixing the foundations of
elementary mathematics, the Devil is in the detail!” Jonathan J. Crabtree
147
Are negative numbers ‘less than zero’?
No. Before the Chinese adopted India’s zero, they used positives and
negative for around 1400 years, with no need to move away from the
idea negative and positive are simply equal and opposite.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
The idea negative numbers are less than zero emerged in 1685 via
Englishman John Wallis. If after marching East 5 yards, a man was
forced back 8 yards, Wallis said in total he advanced 3 yards less then
nothing . Chinese and Indians might have said the man retreated 3 yards
West. (We don’t say negative East.)
148
John Wallis, p.265, A Treatise of Algebra 1685.
© 2018 J. J. Crabtree | www.jonathancrabtree.com149
retreated 3 yards
In our universe, the least quantity you will
ever have of anything is ZERO quantity.
Numbers are only ever counts or measures
of quantities, even if the quantity is a ‘unit’.
Maths is about relationships between quantities
and the quantities don’t have to be the same kind.
Discussion on Brahmagupta’s Laws
150© 2018 J. J. Crabtree | www.jonathancrabtree.com
There’s also quantity of fuel and distance, which generate
the maths called fuel consumption.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Discussion on Brahmagupta’s Laws
For example, if people drive a car,
maths looks at the relationships
between quantities of distance and
time to get average speed.
151
© 2018 J. J. Crabtree | www.jonathancrabtree.com 152
153
© 2018 J. J. Crabtree | www.jonathancrabtree.com 154
© 2018 J. J. Crabtree | www.jonathancrabtree.com 155
© 2018 J. J. Crabtree | www.jonathancrabtree.com 156
© 2018 J. J. Crabtree | www.jonathancrabtree.com 157
© 2018 J. J. Crabtree | www.jonathancrabtree.com 158
ZERO (the equilibrium point where opposing
quantities are equal) is the starting point
of relations between quantities.
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Numbers count or
measure quantities
and the study of …
… relations between
quantities is called
mathematical science.
159
Illustration by AFX Animation
Ryunosuke Satoro
© 2018 J. J. Crabtree | www.jonathancrabtree.com
161
For lectures, events or interviews with
Jonathan J. Crabtree please contact
AFX Animation Kolkata India.
Podo the Puppy says...
© 2018 J. J. Crabtree | www.jonathancrabtree.com
Please give your feedback online
www.jonathancrabtree.com/feedback
www.jonathancrabtree.com/feedback 163

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The Relaunch of Indian Mathematics

  • 1. 1
  • 2. © 2018 J. J. Crabtree | www.jonathancrabtree.com 2
  • 3. In 300 BCE the Greek Euclid of Alexandria defined multiplication as repeated addition. a to the power of b (ab) equals a into itself b times. a into b (a × b ) equals a added to itself b times. © 2018 J. J. Crabtree | www.jonathancrabtree.com 3
  • 4. Zero is defined as a – a ‘a number subtracted from itself’. The Arabic world embraced India’s ideas on Zero and negative numbers. Arabic maths was then adopted by Leonardo Pisano who brought India’s ideas on Zero to Europe. © 2018 J. J. Crabtree | www.jonathancrabtree.com 4
  • 5. © 2018 J. J. Crabtree | www.jonathancrabtree.com 5 Your ‘facts’ are false! Everyone is entitled to their own opinion, yet not to their own facts.
  • 6. Extraordinary Claims Require Extraordinary Evidence © 2018 J. J. Crabtree | www.jonathancrabtree.com 6 ✔
  • 7. •India’s definition of ZERO never made it to either the ancient Arabic world or Europe. © 2018 J. J. Crabtree | www.jonathancrabtree.com 7 •In the Arabic world, India’s ZERO only came to exist as a placeholder, not as the power tool to solve simple problems like +3 minus +4, or –2 minus –4, or –4 minus +2 Extraordinary Claims Extraordinary Evidence...
  • 8. Al-Khwārizmī (c. 780-850) “So they made 9 symbols, which are these: 9 8 7 6 5 4 3 2 1. ... Because one is the root of all number and is outside number. It is the root of number because every number is found by it. ... But it [one] is outside number because it is found by itself, I mean, without any other number.” © 2018 J. J. Crabtree | www.jonathancrabtree.com 8
  • 9. Al-Uqlīdisī (c. 920-980) “Why is zero multiplied by zero equal to zero and zero multiplied by any letter zero? We say that by multiplying zero by zero the aim is only to occupy the place; the same applies for multiplying the letter by zero. We multiply the letter by zero ... to occupy the place, and tell that there is a place and that it is empty. © 2018 J. J. Crabtree | www.jonathancrabtree.com 9
  • 10. 200 years after Brahmagupta, al-Khwārizmī did not accept 1 as a number. Zero as a number? Never! © 2018 J. J. Crabtree | www.jonathancrabtree.com 10 300 years after Brahmagupta, al-Uqlīdisī accepted India’s ZERO as a placeholder, yet not a number. Why?
  • 11. © 2018 J. J. Crabtree | www.jonathancrabtree.com 11 Al-Uqlīdisī means ‘the Euclidist’. He was known for his skill in studying the Greek geometry of Euclid and translating it into Arabic. Around 300 BCE, Euclid defined ‘number’ as a multitude of units. So Euclid’s definition of number came before 0 and 1 were numbers.
  • 12. © 2018 J. J. Crabtree | www.jonathancrabtree.com 12 As we will see, India defined zero as the sum of opposing negative and positive numbers with the same multitude or magnitude. If Arabic and European writers in medieval times really understood India’s zero, where are all the negative numbers in their writings?
  • 13. © 2018 J. J. Crabtree | www.jonathancrabtree.com 13 “I have read a few dozen medieval Arabic books on arithmetic and algebra, and there is no hint of negative numbers in any of them. Zero, too, was not regarded to be a number, but was merely the place holder for an empty place in the representation of a number in Arabic (Indian) notation.” “All numbers in Arabic arithmetic were positive. No Arabic author to my knowledge ever even contemplated the existence of negative numbers.” By email courtesy of Dr. Jeffrey Oaks, Professor of Mathematics on: Medieval Arabic algebra and the mathematics of Greece and medieval Europe
  • 14. © 2018 J. J. Crabtree | www.jonathancrabtree.com 14
  • 15. © 2018 J. J. Crabtree | www.jonathancrabtree.com 15
  • 16. © 2018 J. J. Crabtree | www.jonathancrabtree.com 16 Back to the future...
  • 17. © 2018 J. J. Crabtree | www.jonathancrabtree.com 17
  • 18. 18
  • 19. 19
  • 20. Images courtesy of the British Library. For this talk, Brahmagupta’s Laws of Positives Negatives and Zero have been freshly analysed. 20© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 21. 21© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 22. 22© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 23. Brahmagupta’s 5 Addition Laws AL (saṅkalana) © 2018 J. J. Crabtree | www.jonathancrabtree.com 23
  • 24. positive plus positive is positive AL1 © 2018 J. J. Crabtree | www.jonathancrabtree.com 24
  • 25. negative plus negative is negative AL2 © 2018 J. J. Crabtree | www.jonathancrabtree.com 25
  • 26. positive plus negative is the difference between the positive and the negative AL3 © 2018 J. J. Crabtree | www.jonathancrabtree.com 26
  • 27. when positive and negative are equal the sum is… AL4 © 2018 J. J. Crabtree | www.jonathancrabtree.com 27
  • 28. ZERO AL4 © 2018 J. J. Crabtree | www.jonathancrabtree.com 28 when positive and negative are equal the sum is…
  • 29. “…sunya (ZERO) is neither positive nor negative but forms the boundary line between the two kinds, being the sum of two equal but opposite quantities.” Joseph, G. G. (2016). Indian mathematics: Engaging with the world, from ancient to modern times. World Scientific. p. 208 29© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 30. positive plus zero is positive AL5 part 1 © 2018 J. J. Crabtree | www.jonathancrabtree.com 30
  • 31. negative plus zero is negative AL5 part 2 © 2018 J. J. Crabtree | www.jonathancrabtree.com 31
  • 32. zero plus zero is zero AL5 part 3 © 2018 J. J. Crabtree | www.jonathancrabtree.com 32
  • 33. positive plus zero is positive negative plus zero is negative AL5 zero plus zero is zero © 2018 J. J. Crabtree | www.jonathancrabtree.com 33
  • 34. © 2018 J. J. Crabtree | www.jonathancrabtree.com Brahmagupta’s 5 Addition Laws positive plus positive is positiveAL1 negative plus negative is negativeAL2 positive plus negative is the difference between the positive and negativeAL3 when positive and negative are equal the sum is zeroAL4 positive plus zero is positive negative plus zero is negative zero plus zero is zero AL5 34
  • 35. Following text from: Plofker, K. (2009). Mathematics in India: 500 BCE-1800 CE. p. 151, Princeton, N.J: Princeton University Press. Brahmagupta’s 5 Subtraction Laws SL (vyavakalana). 35© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 36. [If] a smaller [positive] is to be subtracted from a larger positive, [the result] is positive. SL1 © 2018 J. J. Crabtree | www.jonathancrabtree.com 36
  • 37. [If] a smaller negative (is subtracted) from a larger negative, [the result] is negative. SL2 © 2018 J. J. Crabtree | www.jonathancrabtree.com 37
  • 38. [If] a larger [negative or positive is to be subtracted] from a smaller [negative or positive, the algebraic sign of] their difference is reversed - negative [becomes] positive and positive negative. SL3 © 2018 J. J. Crabtree | www.jonathancrabtree.com 38
  • 39. A negative minus zero is negative, a positive [minus zero] positive; zero [minus zero] is zero. SL4 © 2018 J. J. Crabtree | www.jonathancrabtree.com 39
  • 40. When a positive is to be subtracted from a negative or a negative from a positive, then it is to be added. SL5 © 2018 J. J. Crabtree | www.jonathancrabtree.com 40
  • 41. © 2018 J. J. Crabtree | www.jonathancrabtree.com Brahmagupta’s 5 Subtraction Laws A smaller positive subtracted from a larger positive is positive.SL1 A smaller negative subtracted from a larger negative is negative.SL2 If a larger negative or positive is to be subtracted from a smaller negative or positive, the sign of their difference is reversed – negative becomes positive and positive negative. SL3 A negative minus zero is negative, a positive minus zero is positive, zero minus zero is zero. SL4 When a positive is to be subtracted from a negative or a negative from a positive, then it is to be added.SL5 41
  • 42. Seeing is Believing! Applying Brahmagupta’s 5 Addition Laws AL © 2018 J. J. Crabtree | www.jonathancrabtree.com 42
  • 43. – negative + positive© 2018 J. J. Crabtree | www.jonathancrabtree.com 43
  • 44. AL1 positive plus positive is positive © 2018 J. J. Crabtree | www.jonathancrabtree.com 44
  • 45. AL2 negative plus negative is negative © 2018 J. J. Crabtree | www.jonathancrabtree.com 45
  • 46. positive plus negative is the difference AL3 © 2018 J. J. Crabtree | www.jonathancrabtree.com 46
  • 47. 3 holes 7 bumps Podo the Puppy by AFX Animation © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 48. 3 negatives 7 positives Podo the Puppy by AFX Animation © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 49. 3 negatives 7 positives Podo the Puppy by AFX Animation © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 50. So –3 + +7 = +4 3 holes (–3) and 7 bumps (+7 ) leads to 4 bumps (+4 ) Watch the AFX Animation video of Podo the Puppy squaring a circle with rope! © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 51. ZERO ZERO when positive and negative are equal the sum is ZEROAL4 © 2018 J. J. Crabtree | www.jonathancrabtree.com 51
  • 52. plus ZERO AL5 positive plus ZERO negative © 2018 J. J. Crabtree | www.jonathancrabtree.com ZERO + positive = positive, ZERO + negative = negative, ZERO + ZERO = ZERO is positive is negative 52
  • 53. Seeing is Believing! Applying Brahmagupta’s 5 Subtraction Laws SL © 2018 J. J. Crabtree | www.jonathancrabtree.com 53
  • 54. If a smaller positive is subtracted from a larger positive the result is positive. SL1 larger positive minus smaller positive is positive © 2018 J. J. Crabtree | www.jonathancrabtree.com 54
  • 55. If a smaller negative is subtracted from a larger negative the result is negative. SL2 larger negative minus smaller negative is negative © 2018 J. J. Crabtree | www.jonathancrabtree.com 55
  • 56. If a larger positive is to be subtracted from a smaller positive, the sign of their difference is reversed – positive becomes negative. SL3 We don’t have enough positives. So use AL4 and AL5. 3 positives minus 4 positives? © 2018 J. J. Crabtree | www.jonathancrabtree.com 56
  • 57. If a larger positive is to be subtracted from a smaller positive… e.g. positive 3 – positive 4 SL3 AL4 “when positive and negative are equal the sum is zero” AL5 “positive with zero is positive” minus Add ZERO © 2018 J. J. Crabtree | www.jonathancrabtree.com 57
  • 58. SL3 Add ZERO Subtractminus © 2018 J. J. Crabtree | www.jonathancrabtree.com AL4 “when positive and negative are equal the sum is zero” AL5 “positive with zero is positive” 58 If a larger positive is to be subtracted from a smaller positive… e.g. positive 3 – positive 4
  • 59. SL3 Add ZERO Subtract Simplify © 2018 J. J. Crabtree | www.jonathancrabtree.com AL4 “when positive and negative are equal the sum is zero” AL5 “positive with zero is positive” 59 If a larger positive is to be subtracted from a smaller positive… e.g. positive 3 – positive 4
  • 60. SL3 Add ZERO Subtract Simplify © 2018 J. J. Crabtree | www.jonathancrabtree.com AL4 “when positive and negative are equal the sum is zero” AL5 “positive with zero is positive” 60 If a larger positive is to be subtracted from a smaller positive… e.g. positive 3 – positive 4
  • 61. SL3 Add ZERO Subtract Simplify © 2018 J. J. Crabtree | www.jonathancrabtree.com AL4 “when positive and negative are equal the sum is zero” AL5 “positive with zero is positive” 61 If a larger positive is to be subtracted from a smaller positive… e.g. positive 3 – positive 4
  • 62. If a larger positive is to be subtracted from a smaller positive, the sign of their difference is reversed – positive becomes negative. SL3 3 positives minus 4 positives is 1 negative © 2018 J. J. Crabtree | www.jonathancrabtree.com 62
  • 63. If a larger negative is to be subtracted from a smaller negative, the sign of their difference is reversed – negative becomes positive. SL3 We don’t have enough negatives. So use AL4 and AL5. 2 negatives minus 4 negatives? © 2018 J. J. Crabtree | www.jonathancrabtree.com 63
  • 64. If a larger negative is to be subtracted from a smaller negative… e.g. negative 2 – negative 4SL3 AL4 “when positive and negative are equal the sum is zero” AL5 “negative with zero is negative” minus Add ZERO © 2018 J. J. Crabtree | www.jonathancrabtree.com 64
  • 65. SL3 AL4 “when positive and negative are equal the sum is zero” AL5 “negative with zero is negative” Add ZERO Subtractminus © 2018 J. J. Crabtree | www.jonathancrabtree.com 65 If a larger negative is to be subtracted from a smaller negative… e.g. negative 2 – negative 4
  • 66. SL3 AL4 “when positive and negative are equal the sum is zero” AL5 “negative with zero is negative” Add ZERO Subtract Simplify © 2018 J. J. Crabtree | www.jonathancrabtree.com 66 If a larger negative is to be subtracted from a smaller negative… e.g. negative 2 – negative 4
  • 67. SL3 AL4 “when positive and negative are equal the sum is zero” AL5 “negative with zero is negative” Add ZERO Subtract Simplify © 2018 J. J. Crabtree | www.jonathancrabtree.com 67 If a larger negative is to be subtracted from a smaller negative… e.g. negative 2 – negative 4
  • 68. SL3 AL4 “when positive and negative are equal the sum is zero” AL5 “negative with zero is negative” Add ZERO Subtract Simplify © 2018 J. J. Crabtree | www.jonathancrabtree.com 68 If a larger negative is to be subtracted from a smaller negative… e.g. negative 2 – negative 4
  • 69. If a larger negative is to be subtracted from a smaller negative… the sign of their difference is reversed – negative becomes positive. SL3 2 negatives minus 4 negatives is 2 positives © 2018 J. J. Crabtree | www.jonathancrabtree.com 69
  • 70. negative minus zero is negative SL4 4– minus 0– is 4– positive minus zero is positive zero minus zero is zero 3+ minus 0+ is 3+ © 2018 J. J. Crabtree | www.jonathancrabtree.com 70
  • 71. When a positive is to be subtracted from a negative … then it is to be added. –4 – +2 SL5 © 2018 J. J. Crabtree | www.jonathancrabtree.com Add ZERO –4 – +2 = ? 71
  • 72. When a positive is to be subtracted from a negative … then it is to be added. –4 – +2 SL5 © 2018 J. J. Crabtree | www.jonathancrabtree.com Add ZERO Subtract –4 – +2 = ? 72
  • 73. When a positive is to be subtracted from a negative … then it is to be added. –4 – +2 SL5 © 2018 J. J. Crabtree | www.jonathancrabtree.com Add ZERO Subtract –4 – +2 = –6 For you. Show how a negative subtracted from a positive is to be added with +3 – –5 73
  • 74. Brahmagupta’s 4 Multiplication Laws ML (guṇana) © 2018 J. J. Crabtree | www.jonathancrabtree.com Text from: Plofker, K. (2009). Mathematics in India 74
  • 75. ML1 The product of a negative and a positive is negative © 2018 J. J. Crabtree | www.jonathancrabtree.com Brahmagupta multiplies positives and negatives by either adding to zero multiple times or subtracting from zero multiple times. –a × +b –a added to zero b times 75 False from 1570: a into b, (a × b), is a added to itself b times
  • 76. Negative Multiplicand Multiplied by Positive Multiplier –a × +b –a added to zero b times × added to zero times Next, from pictures to equations… –2 × +3 –2 added to zero 3 times 76© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 77. Negative Multiplicand Multiplied by Positive Multiplier –2 × +3 = –2 × (0 + 1 + 1 + 1) –2 × +3 = 0 + –2 + –2 + –2 –2 × +3 = 0 + –6 –2 × +3 = –6 –a × +b –a added to zero b times –2 × +3 –2 added to zero 3 times 77© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 78. Positive Integer Multiplied by Negative Multiplier +2 × –3 Brahmagupta did not say “The product of a positive and a negative is negative”. However, we can demonstrate this via his Laws. +a × –b +a subtracted from zero b times 78© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 79. Positive Multiplicand Multiplied by Negative Multiplier × +a × –b +2 subtracted from zero 3 times +2 × –3 As we don’t have any positive twos to subtract, we first add zero in the form +6 + –6 79© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 80. Positive Multiplicand Multiplied by Negative Multiplier × Next, from pictures to equations… +a × –b +2 subtracted from zero 3 times +2 × –3 80© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 81. Positive Integer Multiplied by Negative Multiplier +2 × –3 +2 × –3 = +2 × (0 – +1 – +1 – +1) +2 × –3 = 0 – +2 – +2 – +2 +2 × –3 = 0 – +6 +2 × –3 = –6 + +6 – +6 +2 × –3 = –6 + 0 +2 × –3 = –6 81© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 82. ML2 The product of two negatives is positive © 2018 J. J. Crabtree | www.jonathancrabtree.com –1 × –1 = +1 A demonstration goes like this… Crabtree,JonathanJ.Snippet:Anew reasonnegativemultipliedbynegativeis positiveVinculum,Vol.52,No.3,Jul2015: 82
  • 83. ML2 © 2018 J. J. Crabtree | www.jonathancrabtree.com Negative Multiplicand Multiplied by Negative Multiplier –a × –b –a subtracted from zero b times –1 × –1 –1 subtracted from zero 1 times 83
  • 84. Brahmagupta Defined ZERO in Law AL4 when positive and negative are equal the sum is ZERO © 2018 J. J. Crabtree | www.jonathancrabtree.com –1 × –1 84 –1 subtracted from zero 1 times + –1+1
  • 85. Brahmagupta Defined ZERO in Law AL4 when positive and negative are equal the sum is ZERO + –1 © 2018 J. J. Crabtree | www.jonathancrabtree.com –1 × –1 –1 subtracted from zero 1 times now prove it equals +1 ∴ –1 × –1 = +1 85 +1
  • 86. ML3 The product of two positives is positive © 2018 J. J. Crabtree | www.jonathancrabtree.com ML4 The product: - of zero and a negative, - of zero and a positive, - or of two zeros is zero. 86
  • 87. © 2018 J. J. Crabtree | www.jonathancrabtree.com Brahmagupta’s 4 Multiplication Laws The product of a negative and a positive is negative.ML1 The product of two negatives is positive.ML2 The product of two positives is positive.ML3 The product of zero and a negative, of zero and a positive, or of two zeros is zero. ML4 87
  • 88. MY ASSESSMENT OF THE WORLD’S PEDAGOGICAL EVOLUTION (628 to Now) © 2018 J. J. Crabtree | www.jonathancrabtree.com 88
  • 89. Brahmagupta’s 4 [Non-Zero] Division Laws DL (haraṇa) © 2018 J. J. Crabtree | www.jonathancrabtree.com 89
  • 90. © 2018 J. J. Crabtree | www.jonathancrabtree.com Brahmagupta’s 4 Division Laws A positive divided by a positive is positive.DL1 A negative divided by a negative is positive.DL2 A positive divided by a negative is negative.DL3 A negative divided by a positive is negative.DL4 90
  • 91. NOTE: Why Non-Zero Division Laws Only? © 2018 J. J. Crabtree | www.jonathancrabtree.com Whilst zero divided by any non-zero number (0/±n), is zero, Brahmagupta says a non-zero number divided by zero(i.e. ±n/0), remains ‘zero divided’. Commentators such as Bhāskara II (1114 –1185) suggested n/0 is infinite or indeterminate. 91
  • 92. © 2018 J. J. Crabtree | www.jonathancrabtree.com MODELS OF DIVISION Partitive Model Equal Groups +12 ÷ +4 Q. If you have 12 things and 4 equal groups, how many things go in each group? A. 3 things go in each group. 12 ÷ 4 = 3 things Partitive Model ✔ 92
  • 93. © 2018 J. J. Crabtree | www.jonathancrabtree.com MODELS OF DIVISION Quotitive Model Repeated Subtraction Q. If you have 12 things, how many times can you subtract 4 things? A. You can subtract 4 things 3 times until you get 0 things. 12 ÷ 4 = 3 times Partitive Model ✔ Quotitive Model ✔ +12 ÷ +4 93
  • 94. © 2018 J. J. Crabtree | www.jonathancrabtree.com METHODS OF DIVISION Equal Groups Repeated Subtraction Equal Groups Equal Groups Repeated Subtraction Equal Groups Repeated Subtraction Repeated Subtraction ✔ ✔ ✔ ✔ ✘ ✘ ✘ ✘ 94
  • 95. © 2018 J. J. Crabtree | www.jonathancrabtree.com MODELS OF DIVISION Partitive Model Equal Groups +12 ÷ –4 Q. If you have 12 positive things and negative 4 groups, how many things go in each group? A. You can’t have a negative number of groups! Equal Groups ✘ Model Fails 95
  • 96. © 2018 J. J. Crabtree | www.jonathancrabtree.com MODELS OF DIVISION Quotitive Model Repeated Subtraction Q. If you have 12 positive things, how many times can you take away 4 negative things? A. You can’t subtract 4 negative things from positive things. Try... +12 – –4 = +16, – –4 = +20, – –4 = +24. i.e. You go the wrong way and never get to zero. +12 ÷ –4 Equal Groups✘ Repeated Subtraction✘ 96 Model Fails
  • 97. © 2018 J. J. Crabtree | www.jonathancrabtree.com PROPORTIONAL COVARIATION, PCV Equal Groups✘ Repeated Subtraction✘ Numbers are counts or measures of standard units. We choose 1. All numbers are measured by the unit called 1. 1 is the multiplicative identity and the divisional identity. 97
  • 98. © 2018 J. J. Crabtree | www.jonathancrabtree.com Equal Groups✘ Repeated Subtraction✘ Our goal is to convert 12/4 into the form n/1 DENOMINATOR To make –4 be +1 we take one of the 4 parts of –4, which is –1 and subtract it from zero to get +1. PROPORTIONAL COVARIATION, PCV 98
  • 99. © 2018 J. J. Crabtree | www.jonathancrabtree.com Whatever we have done to the denominator, we must do to the numerator to keep the number (ratio) NUMERATOR We take one of the 4 parts of +12, which is +3 and subtract it from zero to get –3. PROPORTIONAL COVARIATION, PCV Equal Groups✘ Repeated Subtraction✘ 99
  • 100. © 2018 J. J. Crabtree | www.jonathancrabtree.com Whatever we have done to the denominator, we must do to the numerator to keep the number (ratio) PROPORTIONAL COVARIATION, PCV Equal Groups✘ Repeated Subtraction✘ 100 (Zero Minus Numerator) by (Zero Minus Denominator) –12 +4
  • 101. Multiplication: Whatever we do to the Unit 1 to make the Multiplier b we do to the Multiplicand a to make the Product c. Division: Whatever we do to the Divisor b to make the Unit 1 we do to the Dividend a to make the Quotient c. © 2018 J. J. Crabtree | www.jonathancrabtree.com PROPORTIONAL COVARIATION, PCV 101
  • 102. As –4 is to +1 +12 is to... 102© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 103. © 2018 J. J. Crabtree | www.jonathancrabtree.com 3 MODELS OF DIVISION Equal Groups Repeated Subtraction Proportional Covariation Proportional Covariation Proportional Covariation Equal Groups Repeated Subtraction✔ ✔ ✔ ✔ ✔ ✔ 103 Proportional Covariation ✔ +12 ÷ –4 ✔
  • 105. –2 x –3 = ? (i.e. negative two subtracted three times from zero) What do we do to the standard Unit 1 to make the Multiplier –3? We place three Units and subtract them from zero to make the Multiplier –3. PROPORTIONAL COVARIATION, PCV 105© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 106. –2 x –3 = ? (i.e. negative two subtracted three times from zero) PROPORTIONAL COVARIATION, PCV What do we do to the Multiplicand –2 to make the Product ? We place three Multiplicands and subtract them from zero to make the Product +6. 106© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 107. +2 –3 ? +2 × –3 = ? a × b = ? We start off with +1 in this square
  • 108. Then we put b the Multiplier here +2 × –3 = ? a × b = ? We start off with +1 in this square +2 –3 ?
  • 109. +2 –3 ? Then we put a the Multiplicand here +2 × –3 = ? a × b = ? Then we put b the Multiplier here We start off with +1 in this square
  • 110. To go from +1 to –3 we took 3 Units & changed their sign by subtracting from 0. So, we take 3 a’s and change their sign by subtracting from 0 to make c. +2 × –3 = ? a × b = ? Then we put b the Multiplier here We start off with +1 in this square +2 –3 ? Then we put a the Multiplicand here
  • 111. +2 × –3 = ? a × b = ? +2 –3 ?
  • 112. +2 × –3 = ? a × b = ? +2 –3 ?
  • 113. +2 × –3 = ? a × b = ? +2 –3 ?
  • 114. +2 –3 ? +2 × –3 = ? a × b = ?
  • 115. +2 × –3 = ? a × b = ? +2 –3 ?
  • 116. +2 × –3 = ? a × b = ? +2 –3 ?
  • 117. PCVMultiMat PCVDiviMat 117© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 118. –2 x –3 As +1 is to –3 so –2 is to +6 PROPORTIONAL COVARIATION PCV b a c 1 118© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 119. René Descartes 1596 – 1650 Brahmagupta 598 – 668 Brahmagupta’s ideas were not applied 1000 years later, yet should have been.
  • 120. Copyright © 2016 Jonathan Crabtree All Rights Reserved “For example, let AB be taken as unity, (1), and let it be required to multiply BD (the multiplicand) by BC (the multiplier), I have only to join the points A and C, and draw DE parallel to AC; and BE is the product of this Multiplication.” Applying Indian Logic to Descartes’s Multiplication
  • 121. https://www.geogebra.org/m/wprjkwam Let point B be 0 and line segments on the other side of 0 be negative...
  • 122. https://www.geogebra.org/m/wprjkwam A Negative Multiplicand and a Negative Multiplier result in a Positive Product.
  • 125. © 2018 J. J. Crabtree | www.jonathancrabtree.com 125 www.bit.ly/New-x-Model
  • 126. Q. Why no numbers in Greek Geometry? A. Aristotle Greek Philosopher 384–322 BCE Geometry cannot be proven with arithmetic © 2018 J. J. Crabtree | All Rights Reserved www.jonathancrabtree.com
  • 127. Discussion on Brahmagupta’s Laws © 2018 J. J. Crabtree | www.jonathancrabtree.com A. Even though the numbers are different, both numerators are smaller than their denominators. Q. How can the following fractions be equal? + 1 + 2 = + 4 + 8 127
  • 128. Discussion on Brahmagupta’s Laws If one side has a smaller number on the top and the other side has a larger number on the top, even if the same numbers are used as before, the two sides can’t be equal. + 1 + 2 ≠ + 8 + 4 © 2018 J. J. Crabtree | www.jonathancrabtree.com 128
  • 129. Discussion on Brahmagupta’s Laws Q. Is the following equation correct? + 1 + 2 = − 4 − 8 © 2018 J. J. Crabtree | www.jonathancrabtree.com A. Yes. Therefore, just as +1 < +2 we must accept –4 < – 8, to be consistent with Brahmagupta’s laws and the laws of proportion. The British system has –4 > – 8, which is illogical given positives and negatives are equal and opposite. Brahmagupta’s laws of integer ordering are intuitive logical and correct! 129
  • 130. Discussion on Brahmagupta’s Laws The same number of positives and negatives sum to zero as they are equal and opposite. Therefore today’s integer inequality laws, based on Greek foundations 1000 years older than India’s are out-of-date and sub-optimal. © 2018 J. J. Crabtree | www.jonathancrabtree.com 130
  • 131. Which numbers are greater? or or or or © 2018 J. J. Crabtree | www.jonathancrabtree.com Discussion on Brahmagupta’s Laws © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 132. Which numbers are greater? or or or or x x x xxx xxxx xx xxxx x xxx xx xx xxxxx x © 2018 J. J. Crabtree | www.jonathancrabtree.com Discussion on Brahmagupta’s Laws © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 133. Which numbers are greater? or or or or xx xx x x xx xx x xxx x x xx xx x xxx xx 5+ < 7– 9+ > 4– 1+ < 3– 5+ ≹ 5– xx xx © 2018 J. J. Crabtree | www.jonathancrabtree.com Discussion on Brahmagupta’s Laws © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 134. © 2018 J. J. Crabtree | www.jonathancrabtree.com 1+< 3+ 1–< 3– 2–= 2– 3–>1+ 3+>1– 1–< 3+ 1+< 3– 2+= 2+ 3–>1– 3+>1+ 2+ 2–o=2+ are equal and opposite to 2– 134
  • 135. …to multiply a by integral b is to add a to itself b times Collins Dictionary of Mathematics © 2018 J. J. Crabtree | www.jonathancrabtree.com In book VII, Euclid defines multiplication as ‘when that which is multiplied is added to itself as many times as there are units in the other’ The Development of Multiplicative Reasoning in the Learning of Mathematics 1 × 1 = 2? © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 137. Returning India’s zero reveals unseen patterns. a × +4 = 0 + a + a + a + a a × +3 = 0 + a + a + a a × +2 = 0 + a + a a × +1 = 0 + a a × 0 = 0 a × –1 = 0 – a a × –2 = 0 – a – a a × –3 = 0 – a – a – a a × –4 = 0 – a – a – a – a Integral multiplication involves either repeated addition or repeated subtraction of the multiplicand from zero, depending on the sign of the multiplier. 137© 2018 J. J. Crabtree | www.jonathancrabtree.com The Billingsley ‘virus’of 1570 (BV1570) spread widely! CLICK HERE FOR MORE
  • 138. When explaining a3, Sir Isaac Newton used the Latin word ‘bis’, meaning ‘twice’, so a3 is a twice into itself. Yet because of Henry Billingsley’s mistranslation of Euclid’s definition of multiplication, upon translating from Newton’s Latin into English, the translator changed Newton’s explanation. To match Billingsley’s approach, (thought to be Euclid’s), Newton now reads ‘… the Number 3 in the Quantity a3bb, does not denote that bb is to be taken thrice, but that a is to be thrice multiplied by itself.’ So, today, we find, nonsense definitions of exponentiation that simply do not work! © 2018 J. J. Crabtree | www.jonathancrabtree.com© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 139. © 2018 J. J. Crabtree | www.jonathancrabtree.com 23 ≠ 16 © 2018 J. J. Crabtree | www.jonathancrabtree.com Cube ‘the result of multiplying a number, quantity, or expression by itself three times’. Collins Dictionary of Mathematics If a3 is a into itself three times, we get the sequence a into a, into a, into a. If 23 is 2 into itself three times, we get the sequence 2 into 2, into 2, into 2, which is 16. Just as India’s 0 went missing from definitions of multiplication, we now know 1 went missing from definitions of exponentiation!
  • 140. Returning the identity element one into exponentiation. a+4 = 1 × a × a × a × a a+3 = 1 × a × a × a a+2 = 1 × a × a a+1 = 1 × a a 0 = 1 a–1 = 1 ÷ a a–2 = 1 ÷ a ÷ a a–3 = 1 ÷ a ÷ a ÷ a a–4 = 1 ÷ a ÷ a ÷ a ÷ a Integral exponentiation involves either repeated multiplication or repeated division of the base from one, depending on the sign of the exponent. © 2018 J. J. Crabtree | www.jonathancrabtree.com 140 a+b = 1 into a, b times 2+3 = 1 into 2, 3 times, 1 × 2 × 2 × 2 a–b = 1 by a, b times 2–3 = 1 by 2, 3 times, 1 ÷ 2 ÷ 2 ÷ 2 There is much confusion about cubes and cube roots. CLICK HERE FOR MORE
  • 141. South West Left Down Debts Loss Deaths Emigration Cold Decay Below Zero Less Than Enough Below Ground To the hour Deceleration Head Wind (knots) Under Par (golf) North East Right Up Assets Profit Births Immigration Hot Growth Above Zero More Than Enough Above Ground Past the hour Acceleration Tail Wind (knots) Over Par (golf) Counts or measures of negative units Counts or measures of positive units Simple Symmetries of Quantity ©2018J.J.Crabtree|www.jonathancrabtree.com 141
  • 142. © 2018 J. J. Crabtree | www.jonathancrabtree.com It has been said… “God created the universe from nothing, from Shunya, from Zero” Planet Positron Planet Negatron Wherever opposing quantities or forces are equal you will find zero. 142
  • 143. It’s as if ZERO was split, creating infinite real number lines from ZERO. © 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 144. • China had positives and negatives in the 2nd Century BCE, yet their first maths text with India’s zero, (with a symbol 0) came in 1247 CE in The Mathematical Treatise in Nine Sections, by Qin Jiushao. © 2018 J. J. Crabtree | www.jonathancrabtree.com Discussion on Brahmagupta’s Laws • China used positives and negatives in their mathematics for about1400 years without any concept of a number zero. • The Chinese did not define negatives as less than zero. Their positives and negatives were simply equal and opposite, consistent with science and the philosophy of Yin and Yang. 144
  • 145. Is zero defined as ‘a number subtracted from itself’ (n – n)? No. Brahmagupta AL4 says zero is the sum of equal positive and negative quantities. Zero is defined by addition, (–n + +n) not subtraction, for use with Indian Laws of positives negatives and zero. © 2018 J. J. Crabtree | www.jonathancrabtree.com 145
  • 146. © 2018 J. J. Crabtree | www.jonathancrabtree.com Are lessons on inequalities correct? e.g. (–4 > –7) No. SL3 says if a larger negative is subtracted from a smaller negative the sign of the difference is reversed and negative becomes positive. We prove – 4 > –7 false by contradiction. Assume –4 > –7 true. We subtract larger from smaller as –7 – –4 and the difference is –3. As the sign of the difference is NOT reversed we cannot assume –4 > –7 true. Thus –4 < –7 as seems obvious. (A debt of ₹400 is less than a debt of ₹700.) Brahmagupta’s SL3 also holds for greater positive from smaller positive as +4 – +7 = –3 and the sign is reversed as SL3 states. 146
  • 147. Are negative numbers ‘less than zero’? No. Numbers represent count or measures of quantities, even abstract units. The big bang created matter and antimatter. Equal in magnitude, electrons have negative charge and positrons have positive charge. © 2018 J. J. Crabtree | www.jonathancrabtree.com When antimatter and matter meet, they annihilate each other, producing energy. It is said “God made the Integers”. Those integers are consistent with physics. NOTE asymmetry between matter versus antimatter in universe = Baryon asymmetry “If God made the Integers, when it comes to fixing the foundations of elementary mathematics, the Devil is in the detail!” Jonathan J. Crabtree 147
  • 148. Are negative numbers ‘less than zero’? No. Before the Chinese adopted India’s zero, they used positives and negative for around 1400 years, with no need to move away from the idea negative and positive are simply equal and opposite. © 2018 J. J. Crabtree | www.jonathancrabtree.com The idea negative numbers are less than zero emerged in 1685 via Englishman John Wallis. If after marching East 5 yards, a man was forced back 8 yards, Wallis said in total he advanced 3 yards less then nothing . Chinese and Indians might have said the man retreated 3 yards West. (We don’t say negative East.) 148
  • 149. John Wallis, p.265, A Treatise of Algebra 1685. © 2018 J. J. Crabtree | www.jonathancrabtree.com149 retreated 3 yards
  • 150. In our universe, the least quantity you will ever have of anything is ZERO quantity. Numbers are only ever counts or measures of quantities, even if the quantity is a ‘unit’. Maths is about relationships between quantities and the quantities don’t have to be the same kind. Discussion on Brahmagupta’s Laws 150© 2018 J. J. Crabtree | www.jonathancrabtree.com
  • 151. There’s also quantity of fuel and distance, which generate the maths called fuel consumption. © 2018 J. J. Crabtree | www.jonathancrabtree.com Discussion on Brahmagupta’s Laws For example, if people drive a car, maths looks at the relationships between quantities of distance and time to get average speed. 151
  • 152. © 2018 J. J. Crabtree | www.jonathancrabtree.com 152
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  • 154. © 2018 J. J. Crabtree | www.jonathancrabtree.com 154
  • 155. © 2018 J. J. Crabtree | www.jonathancrabtree.com 155
  • 156. © 2018 J. J. Crabtree | www.jonathancrabtree.com 156
  • 157. © 2018 J. J. Crabtree | www.jonathancrabtree.com 157
  • 158. © 2018 J. J. Crabtree | www.jonathancrabtree.com 158
  • 159. ZERO (the equilibrium point where opposing quantities are equal) is the starting point of relations between quantities. © 2018 J. J. Crabtree | www.jonathancrabtree.com Numbers count or measure quantities and the study of … … relations between quantities is called mathematical science. 159
  • 160. Illustration by AFX Animation Ryunosuke Satoro
  • 161. © 2018 J. J. Crabtree | www.jonathancrabtree.com 161
  • 162. For lectures, events or interviews with Jonathan J. Crabtree please contact AFX Animation Kolkata India. Podo the Puppy says...
  • 163. © 2018 J. J. Crabtree | www.jonathancrabtree.com Please give your feedback online www.jonathancrabtree.com/feedback www.jonathancrabtree.com/feedback 163