Round Decimals to the Nearest Tenth or Whole Number

In this activity, we will be learning how to round decimal numbers. 

 

Numbers with 2 decimal places have 2 digits after the decimal point.

To round one of these numbers to the nearest 1 decimal place number think of a number line.

 

Numbers ending in 1, 2, 3, 4 round DOWN.

Numbers above this, those ending in 5, 6, 7, 8 and 9 round UP.

Remember that halfway numbers, such as 7.50 round UP.

 

 

Here 7.35 is between 7.3 and 7.4, but rounds up to 7.4 to one decimal place.

 

We can also round decimal numbers to the nearest whole number using the same method.

1.28 would round down to 1 because it has two tenths.

But, 1.82 would round up to 2 because it has eight tenths.

 

Let's try some example questions. 

 

Example 1

Round 12.63 to one decimal place.

 

Answer

12.63 is between 12.6 and 12.7, but is closer to 12.6.

There is a 3 in the second decimal place spot, so it rounds down.

12.63 rounds down to 12.6.

 

Example 2

Round 10.78 to the nearest whole number.

 

Answer

10.78 is between 10 and 11, but is closer to 11.

The 7 in the tenths place means that it will round up.

10.78 rounds up to 11

 

Example 3

Think of a number with 2 decimal places which rounds to 5 whole ones?

 

Answer

There are quite a few that would be correct for this one but we'll stick with giving just one answer!

4.54 would round to 5 because it has a 5 in the tenths place so it will round up to 5.

 

Now it's your turn to try some questions like this.