Practise Different Methods of Subtraction

In this activity, we will be answering mixed questions all about subtraction.

 

Subtracting is all about taking numbers away.

 

Example 1

Work out:

 

21 - 7

 

Answer

You probably know that 11 - 7 = 4, so

 

21 - 7  = 14

 

Example 2

What is the missing number?

 

___ - 12 = 29

 

Answer

Here, we use the opposite of subtraction, which is addition, to work out the starting number of the given subtraction.

 

We must work out 12 + 29.

 

Add the units 2 + 9 = 11

Add the tens 10 + 20 = 30

 

Add the two results 11 + 30 = 41

 

12 + 29 = 41

 

41 - 12 = 29

 

 

Example 3

Work out:

 

43 - 29

 

Answer

Here we subtract 30 instead of 29.

Then we add 1 back at the end because we subtracted 1 too many by subtracting 30 instead of 29!

 

43 - 30 = 13

13 + 1 = 14

 

43 - 29  = 14

 

These are just a few tips to help you to work out subtraction problems in your head. Let's try putting them into practice in the questions that follow.