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Everyday maths 2

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8.1 Order of operations

The order in which you carry out operations can make a big difference to the final answer. When doing any calculation that involves doing more than one operation, you must follow the rules of BIDMAS in order to arrive at the correct answer.

Figure _unit2.8.3 Figure 22 The BIDMAS order of operations

Case study _unit2.8.1 B: Brackets

Any calculation that is in brackets must be done first.

Example:

Extract _unit2.8.1

2 × (3 + 5)

2 × 8 = 16

Note that this could also be written as 2 (3 + 5) because if a number is next to a bracket, it means you need to multiply

Case study _unit2.8.2 I: Indices

After any calculations in brackets have been done, you must deal with any calculations involving indices or powers i.e.

32 = 3 × 3

or

43 = 4 × 4 × 4

Example:

3 × 42

3 × (4 × 4)

3 × 16 = 48

Case study _unit2.8.3 D: Divide

Next come any division or multiplication calculations. Of these two calculations, it does not matter which you do first.

Example:

16 − 10 ÷ 5

16 − 2 = 14

Case study _unit2.8.4 M: Multiply

Example:

Extract _unit2.8.5

5 + 6 × 2

5 + 12 = 17

Finally, any calculations involving addition or subtraction are done. Again, it does not matter which of these two are done first.

Example:

24 + 10 − 2

34 − 2 = 32

or

24 + 8 = 32

Activity _unit2.8.1 Activity 18: Using BIDMAS

Now have a go at carrying out the following calculations yourself. Make sure you apply BIDMAS!

1. 4 + 3 × 2

2. 5 (4 − 1)

3. 36 ÷ 32

4. 7 + 15 ÷ 3 − 4