NUMBER

Negative Number Arithmetic

Negative Number Arithmetic

GCSE Maths revision : Numbers

To do algebra (especially graphs) for GCSE maths revision, you will need to start learning how to work with negative number arithmetic. You will also need to know basic facts about how to add, subtract, multiply and divide with negative numbers. The basics are below so let getting-in show you with their useful GCSE maths revision notes;

There are a number of rules you need to follow in order to add and subtract negative numbers.

When you add a negative number it’s the same as subtracting it:

4 + (- 3) = 1

The negative sign cancels out the plus sign.

If you want to subtract a negative number it’s the same as adding it:

4 – (- 3) = 7 or (-4) – (- 3) = -1

Two minuses make a plus.

The rules for multiplying negative numbers are as follows:

positive x positive = positive

For example: 5 x 6 = 30

positive x negative = negative

For example: 5 x -6 = -30

negative x positive = negative

For example: -5 x 6 = -30

negative x negative = positive

For example: -5 x -6 = 30

As you can see, two negatives make a positive while one negative and a positive make a negative.

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Negative numbers when multiplying out brackets

GCSE Maths revision : NumbersIn your exam you could get asked to multiply out brackets. For example: multiply out 6(4 + 3x)

For this question you need to multiply each term in the bracket by what’s outside the bracket. This means you multiply the 4 and 3x by 6 to get:

24 + 18x

Multiplying out with negative numbers is the same principle however, it’s important to remember that:

minus x minus = plus

minus x plus or plus x minus = minus

For example: multiply out -4(5y – 3)

-4 x 5y = -20y

-4 x -3 = 12

So the answer is: -20y + 12