In this activity, we will be rounding decimal numbers to the nearest whole numbers and then estimating the answer to an addition.

Remember when rounding decimals to whole numbers, we need to look at the first digit on the right of the decimal point. If it is below 5, it will round down. If it is 5 or above, it will round up.

For example:

27.3 will round down to 27, but 27.6 will round up to 28.

32.28 will round down to 32, but 18.63 will round up to 19.

Example

Estimate the answer to the addition by first rounding both decimals to the nearest whole numbers.

10.3 + 27

A

+

B

=

C

Answer

10.3 + 27

10

+

27

=

37

Let's have a go at the questions.