Round Decimals to Nearest Whole Numbers Before Multiplying

In this activity, we will be rounding decimal numbers to the nearest whole numbers in order to estimate the answer to a multiplication.

For example

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

2.25 x 1.41

A

X

B

=

C

2.25 x 1.41

2

x

1

=

2

We need to remember our rules for rounding decimals to whole numbers for this activity!

If the number immediately after the decimal point, in the tenths column, is 5 or more, we round up the number in the ones column.

If the number in the tenths column is below 5, the number in the ones column will not change.

So, in the example above, both 2.25 and 1.41 have numbers in the tenths column that are below 5, so this means they round down to the whole numbers 2 and 1.

Are you ready to get rounding?