### What are Negative Numbers?

A **negative number** is a number **less than zero**.

**Negative numbers** are written with a **minus** sign in front, like this:

-9

They can be also written as **minus 9** or **negative 9**, these both mean the same thing: **-9**.

This **number line** shows the numbers counting **up from zero**:

You need to know that there are numbers **below zero**. They are the **negative numbers**. Here is the number line also showing the negative numbers:

### Ordering Negative Numbers

Ordering negative numbers is easy but remember negative numbers get lower in value as the numbers progress… so -4 has a lower value than -1.

Moving from zero down the number line, you can see that -4 is a **smaller** number than -1. This can seem strange at first as 4 is a bigger number than 1. However remember these are **negative numbers** and -4 is smaller than -1, just look at it’s position on the number line. When asked to place negative numbers in order it is important to remember this.

Example

Question: Place the following numbers in order of size:

-2, 4, -6, 1, 5

We must first remember the number line, you can quickly draw one out if you need to and then look at the position of the numbers you are comparing:

From the diagram we can see the order of size:

-6, -2, 1, 4, 5

### Adding or Subtracting Negative Numbers

When adding or subtracting negative numbers always draw a **number line**

**Move up** the number line when **adding** on numbers and **move down** the line when **subtracting**. It is worth remembering that the number line we draw is only a part of the line, it can go on for ever in both directions.

Take a look at the sum below:

5 minus 8 = -3

If we draw a number line and then work our way back from 5 by 8 numbers we can see the result **-3**:

### Temperature Questions

Questions about **temperature** often involve **negative numbers**.

A common use of **negative numbers** is when we look at a thermometer and see negative temperatures. **The temperatures below zero are the negative numbers**.

For example **-2°C** is a temperature **two degrees below zero**.

**°C** means **degrees Celcius** and this is a unit of measuring temperature.

When asked to **add or subtract** negative temperatures you can draw a **number line** and use the method of adding or subtracting negative numbers – don’t be put off by the °C symbol, the numbers can be treated like any other number.