# Algebra - Order of Operations

## BODMAS or BIDMAS

This all sounds very complicated and confusing, but as with most other topics,
the key is to break it down and work through it slowly and thoroughly.

### Why do we need an Order of Operations?

Look at this calculation ... 5 + 2 x 4

If you work from left to right - you would get, 5 + 2 = 7 and then 7 x 4 = 28

try this with a scientific calculator .... the result is 13!

Which answer is correct? You guessed it - the calculator. It did the multiplication first,
2 x 4 = 8, and then added the 5, 8 + 5 = 13

So, we need to know which calculation to do first - which order to do the operations in.

The Order of Operations is just a set rules to tell you which order you must do operations (like add, subtract, multiply etc) to get the correct answer.

# A S

### Lets work through an example ... 10 + (8-6) x 5

1st - Deal with the brackets, 8 - 6 = 2, which results in ... 10 + 2 x 5

2nd - Any powers? No

3rd - Any multiplications or divisions? Yes -
work them out, 2 x 5 = 10 leaving ... 10 + 10

Lastly, Any additions or subtractions? Yes, work them out, 10 + 10 = 20

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### How about a tougher one? ... 9 - (5 x 2 ²) ÷ 5

1st - Deal with the brackets. Inside the brackets there are two operations, a                                multiplication and a power. You must do the power first and then the                                multiplication.     2² = 2 x 2 = 4 and then 5 x 4 = 20 leaving   9 - 20 ÷ 5

2nd - Any powers left? No

3rd - Any divisions or multiplications? Yes ...   20 ÷ 5 = 4 leaving 9 - 4

Lastly, any subtractions or additions? Yes ..... 9 - 4 = 5

Practice working with BODMAS / BIDMAS
with these worksheets from Mathsblog