1. Urdhva-Tirayk Sutra
Multiplication
Urdhva-Tirayak Sutra
Principle : (ax2+bx+c)*(dx2+ex+f)=
x4*ad+x3(ac+bd)+x2(af+bc+cd)+x(bf+ce)+cf
Explanation: - Any number can be written as the sum of digits multiplied by a power of 10
e.g. 8 = 100*8
18= 101*1+100*8
218 = 102*2+101*1+100*8 etc.
- Replace x by 10 in the above equation, and a, b,c etc by digits.
- The left hand side of the equation represents the multiplication of two
numbers (First one is the multiplicand and the second one, multiplier)
- The right side of the equation is the result (Product)
- The coefficient of x4 is the first digit of the product, the coefficient x3 is the
second digit of the product and so on.
(Contd.)
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2. Urdhva-Tirayk Sutra
Thumb Rule: A close observation of the equation of the previous slide would
reveal the following thumb rules for multiplication of two numbers with three
digits each;
- The first digit of the product is got by the vertical multiplication of the first digits from
the left side.
- The second digit is got by the cross-wise multiplication of the first two
digits and by the addition of the two products
- The third digit is obtained by summing the results of multiplication of the first digit of
the multiplicand by the last digit of the multiplier, of the middle one by the middle one
and the last one by the first one.
- The fourth digit is obtained by summing the results of multiplication of the second
digit of the multiplicand by the third digit of the multiplier and the third digit of the
multiplicand by the second digit of the mutiplier
-The last digit of the product is obtained by multiplying the last digit of the
multiplicand by the first digit of the multiplier.
This rule can be extended to numbers containing any number of
digits.
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4. Urdhva-Tirayk Sutra
Examples:
Note:In Example 3, the sum of the
1. 12*13 = 1*1|1*3+2*1|2*3 products gives 30 and the digit in
= 1 | 5 | 6 = 156 ten’s place i.e. 3, is Carried forward
to the left of the ‘ | ’ and added to 9.
Similarly, 7*3 gives 21 and the 2,
2. 23*21 = 2*2 | 2*1+3*2 | 3*1 being a carry, is added to the 0 on
= 4 | 8 | 3 = 483 the left of the ‘ | “.In these
3 37*33 = 3*3 | 3*3+7*3 | 7*3 exercises,
the ‘Carry’s’ are shown as
= 9 |30 | 21 subscripts and ‘negative digits’ with
= 9+3 | 0 +2| 1 a bar on the top of the digit, for
= 1221 better understanding.
4. 111*111 = 1*1 | 1*1+1*1 | In Example 4, the digits of the
1*1+1*1+1*1 | multiplicand and multiplier are
1*1+1*1 | 1*1 having the same color code, but the
Digits in the multiplier are in Bold’.
=1 | 2 | 3 | 2 | 1 This would enable a better
=12321 understanding of the pattern of
cross multiplications of digits from
multiplicand and multiplier in a
systematic manner.
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6. Urdhva-Tirayk Sutra
Owing to their relevance to this context, a few algebraic examples of the
Urdhva-Tiryak type are given below:
1. (a+b)*(a+9b)
a+b
a+9b
a2+10ab+b2
2. (a+3b)*(5a+7b)
a+3b
5a+7b
5a2+22ab+21b2
3. (3x2+5x+7)*(4x2+7x+6)
3x2+5x+7
4x2+7x+6
12x4+41x3+81x2+79x+42
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7. Urdhva-Tirayk Sutra
The Use of the Vinculum
The multiplications by digits higher than 5 may some times be facilitated by the
use of the vinculum.
Note: A negative digit in a number (not negative number) is represented by a bar on the top of the
digit. This is called vinivulum
Ex: 1. In the number 576, the digits 7 and 6 can be written with viniculum as follows;
500+76
=500+(100-24)
=600-20-4
=624
Ex 2. The number 73 can be written as follows;
73 = 70+3
= (100-30)+3
= 1+(-3)+3
=1 3 3
But the vinculum process is one which one must very carefully practice,
before one resorts to it and relies on it.
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