NUMBER

Long Division and Multiplication

Long Division and Multiplication

Order of operation

With calculations, you need to be careful in what order you carry them out in order to get the right answer.

GCSE Maths revision : Numbers

And so you use BIDMAS:

Brackets, Indices, Division, Multiplication, Addition and Subtraction

For example: 3 x (4 + 2)

Following BIDMAS: brackets first THEN multiplication.

3 x 6 = 18

If you didn’t follow this rule and ignored the brackets you’d end up with the wrong answer:

12 + 2 = 14

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Long division

GCSE Maths revision : NumbersWith long division you also have two methods to choose from:

  • – the ‘traditional’ method
  • – repeated subtraction

The traditional method of long division is like that used for normal division. However, you need to write your remainder underneath as opposed to on top.

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Long multiplication

GCSE Maths revision : NumbersFor multiplication there are two main methods you can use:

  • – the ‘traditional’ method
  • – the boxes method

For your exam you’ll only need to know one of them so choose the one you feel most comfortable with.

The traditional method involves multiply the tens and the units separately and then adding them together at the end.

For example: 243 x 56

First of all you need to multiply the units:

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Then, you multiply the tens. But, before you start to write down your answer you need to add a 0 in the right hand column. This is because you’re multiply by, in this example, 50.

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The final stage is to add up both your answers:

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So the answer to 243 x 56 = 13608.

The boxes method involves splitting each of the numbers into its separate parts. These are then put into a ‘box’ and each part is multiplied. For this method you have to be confident with multiplying by powers of ten.

243 x 56

200 40 3
50 10,000 2000 150
6 1200 240 18

Then you add each of these numbers up:

GCSE Maths revision : Numbers