Numbers, units and arithmetic

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# 3.5.2 With or without brackets

Brackets are not always given in a calculation, and there are rules which tell you in which order to do the calculations in the absence of brackets. The following is the order that scientific calculators normally use.

## Calculations are performed in the following order:

Brackets;

Powers (e.g. squaring or cubing a number);

Division and Multiplication (performed in the order written, left to right);

Addition and Subtraction (performed in the order written, left to right).

If you have a calculator handy, check that it follows these rules.

## Example 16

Calculate 10 + 3 × 7.

Multiplication is done before addition (unless brackets tell you otherwise) so

10 + 3 × 7 = 10 + 21 = 31.

Sometimes brackets are implied in division. For example,

MU120_4M1

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