Understand the Order of Operations Using BIDMAS

What's the correct order to do this calculation?

3 + 7 x 10 

 

If we add first, the answer would be 100.

But if you multiply first, the answer would be 73.

 

 

We need to have an order in which we all do calculations, so everyone does it the same way. 

This diagram below shows the correct order in which we do calculations, starting at the top working down.

 

 

We can use BIDMAS to help us remember the order.

 

Example: 

4 - 2 x 3

The diagram shows x comes before -, so we do 2 x 3 = 6 first.

Then we subtract, so 4 - 6 = -2

So, 4 - 2 x 3 = -2

 

Example: 

3 x (4 + 5)² 

The diagram shows that the brackets are first. 

4 + 5 = 9

 

Indices come next:

9² means 9 x 9 = 81

 

Finally we do 3 x 81 = 243.

 

So,  3 x (4 + 5)² = 243

 

Example:

(2 x 5) - (3 x 3) + 1

 

Brackets first: 2 x 5 = 10 and 3 x 3 = 9 

There's a - and a + and they're on the same level, so we do them left to right.

10 - 9 + 1 = 2

So, (2 x 5) - (3 x 3) + 1 = 2

 

Happy with that?

 

 

Let's give it a go.