Practise Combined Addition and Subtraction of Decimals

In this activity, we will learn how to do combined addition and subtraction of decimal numbers.

 

 

Remember to keep the decimal point and equivalent digits lined up in the correct columns.

Any gaps that are left in the calculation should be filled in with zeros.

 

For example:

36.5 - 4.742

We need to write the two numbers so that the decimal points are lined up, and then fill in the gaps with zeros.

 

We can then do the sum as a normal subtraction sum. Make sure that you line up the decimal point correctly in the answer!

 

36.500 -

 04.742     

---------------

31.758

 

Sometimes, we have more complicated calculations to do that involve both addition and subtraction.

 

Example

 

579.6 - 23.02 + 614.7 - 11 = _________

 

Answer

This can be worked out in several different ways.

One way is to identify the additions and the subtractions.

 

579.6 - 23.02 + 614.7 - 11

 

Then add the blue numbers to get 579.6 + 614.7 = 1194.3

Then add the red numbers to get 23.02 + 11 = 34.02

Then subtract 1194.3 - 34.02 = 1160.28

 

Let's have a go at some questions.