What you need to know

Things to remember:

  • We do what is inside the brackets first.

Previously we have heard the term “BIDMAS”, which tells us in what order we do our operations:

Brackets
I
ndices
D
ivision
M
ultiplication
A
ddition
S
ubtraction

 

Here, we will focus on brackets. Because brackets are at the top of the list, this tells us that we have to do what is in our brackets first.

Find the value of the following expression

(11-3)\div2

Reading down our BIDMAS list we can see that we have to do the brackets first.

11-3=8

(11-3)\div2=8\div2

And now, we can just do the division as normal

8\div2 =4

(11-3)\div2=4

But, what happens if we have two brackets?

Find the value of the following expression

 

(12+5)-(3-9)

Because we have two brackets, which one do we do first?… It doesn’t matter! Let’s start with the first one.

(12+5)-(3-9) =17-(3-9)

Now we have to do the second bracket

17-(3-9)=17 - -6

And now we can do the subtractions as usual (Remember, this will become an addition)

17 - -6=17+6=23

(12+5)-(3-9)=23

Now let’s try the second bracket first.

(12+5)-(3-9) =(12+5) - -6

(12+5) - -6=17 - -6

17 - -6 = 17 +6 =23

We got the same answer!

Example Questions

(7-3)\times5=4\times5 =20

(8+3)+(1-7)=11+(1-7)=11+-6=11-6=5

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