# Subtracting negative numbers

## Home learning focus

In this lesson you will learn how to subtract negative numbers.

This lesson includes:

- a learning summary
- two activities

# Learn

## Recap: Subtracting positive numbers

You can use a number line to help you subtract positive numbers.

Start from **0** and find the starting number in the calculation, and locate it on the number line.

When **subtracting** positive numbers, count to the **left** from this starting number by the next number in the calculation.

## Example

Let's look at an example.

Calculate 4 – 5 – 3

Starting from zero, count up to 4.

Then subtract 5.

Then subtract 3.

So, 4 – 5 – 3 = –4

The answer is **–4**.

## Calculations with two signs next to each other

Sometimes a calculation will have two signs, either + or –, next to each other.

For example:

- 6 + –3
- 4 – –3
- 6 – +3

**If the signs are different, you always subtract.**

**If the signs are the same, you always add the numbers together. **

- 6 + –3 = 6 – 3 = 3
- 4 – –3 = 4 + 3 = 7
- 6 – +3 = 6 – 3 = 3

## Subtracting negative numbers

In a calculation, if the signs are the same you always **add** the numbers together. So two negatives always equal a positive.

Therefore, 4 – –3 is the same as 4 + 3, which equals 7.

### More examples

5 - -15 = 5 + 15 = 20

-5 - -15 = -5 + 15 = 10

# Practise

## Activity 1

**Negative numbers in context**

Have a go at this worksheet from Whizz Education. You can print it out or write your answers on a piece of paper.

You will answer equations using negative numbers and two – signs.

## Activity 2

**Negative number pyramids - subtraction**

Have a go at this worksheet from Teachit. You can print it out or write your answers on a piece of paper.

You have to complete the missing numbers in each pyramid. Subtract the two adjacent cells left to right to get the value of the cell above.

# There's more to learn

Have a look at these other resources around the BBC and the web.