Practise Adding and Subtracting with Negative Numbers

We are going to practise adding and subtracting positive and negative numbers in this activity.  

 

Let's start with simple additions.

We can use a number line to help us.

When we add a number on a number line, we move to the right and when we subtract, we go to the left.

 

To work out -3 + 5  we start at -3 on a number line and count forward 5 to get to 2.

 

 

 

So   -3 + 5 = 2

 

 To work out -4 - 5, we start at -4 on a number line and count back 5 to get to -9.

 

 

So   -4 - 5 = -9

 

However, subtracting a negative number is the same as adding a positive. The answer may be positive or negative depending on the size of the number. 

This means that if we have the question 5 - - 3 this is the same as, 5 + 3, since subtracting a negative number is the same as adding.

 

Below is a table to help you remember this rule. 

 

 

Example 1

4 - 5 =  - 1 This can easily be done using a number line. 

 

Example 2

10 - - 4 = 14. Since we have a subtraction next to a negative number, we need to add 10 to 4, giving us 14.  

 

Example 3

12 + -2 = 10. Since we have an addition next to a negative number, we need to subtract 2 from 10. 

 

Would you like to start answering some questions now? Best of luck!