What are negative numbers?
Let's look at one example, the weather. On a cold December night you can watch the thermometer as the temperature drops, as the numbers go down:
2 degrees, 1 degree, zero degrees
But what happens to the numbers if it gets even colder? The temperature and the numbers keep going down!
The numbers below zero are called negative numbers
A negative number is less than zero.
We write negative numbers like this:
negative 2 is the same as -2
The dash is the negative sign. It is usually written slightly shorter and a little higher up than a normal minus signs. But on the internet and in newspapers you will see it written using a minus sign.
Sometimes negative numbers are called minus numbers, careful you don't confuse these with subtraction.
Positive numbers
You already use positive numbers all the time! But, unlike negative numbers you don't have to put a + sign in front of them. Here are some examples of positive numbers:
3, 46, 689, 1 982
A positive number is more than zero.
Why do negative numbers 'get bigger'?
As you extend a number line showing negative numbers, they seem to get 'bigger'.
The numbers seem to increase in value as they go down the number line.
But as the negative number gets bigger, the value gets lower. -10 is a larger number than -5, so it is further below zero. If you look at the number line you can see that -10 is less than -5.
If it helps you remember, think about the weather. As the temperature gets lower the negative numbers seem to get bigger.
Freezing point of water
On a weather forecast temperatures are given in degrees Celsius. Sometimes temperatures are called degrees centigrade, which is the same scale.
You can use a short hand for writing temperatures. You use the degree sign ° and C for Celsius. For example you write the temperature 8 degrees Celsius as 8°C.
When water turns to ice it freezes. The temperature water freezes at is zero degrees Celcius, that's 0°C. Here are some other common temperatures:
Water freezes at 0°C
Below and above freezing
Negative temperatures are called below freezing and positive temperatures are above freezing.
Reading a thermometer
A thermometer is something that is used to measure temperature. When you've been to the doctors they might have taken your temperature with a thermometer. Or you might have one at home showing how hot, or cold, it is inside your house.
Thermometers come in all shapes and sizes. The digital ones give the temperature in numbers, such as 5°C.
With other thermometers you have to read off the scale - the numbers along the side
Negative numbers glossary
Here are some words you'll come across when working with negative numbers
A negative number is less than zero.
-100, -25, -12 and -4 are all negative numbers.
A positive number is more than zero.
4, 12, 89 and 568 are all positive numbers.
The negative sign goes in front of a negative number.
Negative 4 is the same as -4.
° is the symbol for degree.
Celsius or C is a scale for measuring temperature.
6 degrees Celsius is the same as 6°C.
Centigrade is another name for Celsius.
A thermometer is something used to measure temperature.
The thermometer showed the temperature as -5°C
Water freezes, turns solid into ice, at 0°C
Negative temperatures are called below freezing.
Positive temperatures are called above freezing.
When there is a temperature increase it gets warmer.
When there is a temperature decrease it gets colder.
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