For teaching and learning.

1. McCourt 2004
Objective
Be able to approximate
numbers to a given
number of decimal places.

2. McCourt 2004
Round the following number to 1dp
6.348
Firstly, highlight
the number to
the first number
after the
decimal point
So we have
6.3
But is this the
answer?
Now look at
the number
immediately
after where
we stopped
highlighting
If this number is
a 0, 1, 2, 3 or 4
we don’t have
to do anything
else and we
have our
answer.

3. McCourt 2004
Round the following number to 1dp
6.348 = 6.3 (1dp)

4. McCourt 2004
What if the red number was a
5, 6, 7, 8 or 9?
Lets look at an example

5. McCourt 2004
Round the following number to 1dp
9.2721
Firstly, highlight
the number to
the first number
after the
decimal point
So we have
9.2
But is this the
answer?
Now look at
the number
immediately
after where
we stopped
highlighting
If this number is
a 5, 6, 7, 8 or 9
we increase the
last digit by
one.
So 9.2 becomes
9.3

6. McCourt 2004
Round the following number to 1dp
9.2721 = 9.3 (1dp)

7. McCourt 2004

8. McCourt 2004
Write the following numbers
correct to 1 decimal place
1) 4.529
2) 17.583
3) 2.336
4) 0.0732
5) 0.8499
6) 32.6678
7) 12.4012
8) 0.07822
9) 143.4273
10) 2.3056
11) 9.7882
12) 1.4911
What about two decimal
places? And three?