GCSE Maths BIDMAS
Introduction
As a part of your gcse maths you need to be aware of GCSE Maths BIDMAS, which is also known as BODMAS. It is telling you the order in which calculations are performed.
B – Brackets are always performed first
I/O – indices or order then follow
M – multiplication
A – addition
S – Subtraction
Powers are generally written as a small number in the top right next to a number (or letter) such as 4^3. This means that the number 4 is being multiplied by itself 3 times i.e. 4 ×4 ×4.
Roots, especially that of square roots are shown with the symbol √. There are certain square numbers that you should know such as 22, 32, 42, 52….122. knowing these will help you quickly answer questions such \sqrt{25}, \sqrt{121} and \sqrt{36}
GCSE Maths BIDMAS - An Example
Take a look at the following GCSE Maths BIDMAS question:
Here you need to follow the rules of BIDMAS. That means that the multiplication must be done first i.e. 4 ×3=12 and then the addition of 2 can be performed to give 14.
Example
Take a look at the following question:
It is important to realise that you do not perform the calculations in the order that is written.
If you did, then 20-12=8 then 8 ÷4=2
However, following the rules of BIDMAS means that the division must be performed first. 12 ÷4=3. So you then have 20-3=17.
As you can see, two very different results have been obtained. So remember to follow the rule of BIDMAS when performing calculations like this.
Example
Take a look at the following question:
With questions like this it can sometimes be a case of trial and error.
If you have the brackets so that you have 4+5 ×2+3. Then using BIDMAS means that you first have to calculate the brackets which will then give 9 ×2+3.
Again following BIDMAS this would give 18+3=21 which does not give 29. So the positioning of the brackets does not work.
What if the brackets are positioned so that you have 4+5 × 2+3?
Following BIDMAS rules the brackets will give 5. You then have the calculation 4+5 × 5.
Now performing the multiplication give 25.
Finally you have 4+25=29 which is the required result so the positioning of the brackets work. Do not guess where to place the brackets, insert a pair of brackets and follow the rules to see if you obtain the desired result.
Example
Take a look at the following GCSE Maths BIDMAS question:
There are certain rules that you must follow when it comes to powers or indices. In this case you cannot just add the 5 and the 2 together or indeed the powers.
You need to find the value of 5^2 which is 25 and also the value of 2^3=2 \times 2 \times 2=8
Question Practice
Try the following questions on your own before looking at the solution.
Question Practice Solution
Here you first need to calculate each bracket first
18 ÷3=6 and 20 ÷5 =4
So you then have 6+4=10
Using BIDMAS the division needs to be performed first so 8 ÷4=2
Then 7+2=9
Using BIDMAS the multiplication needs to be done first so 5 ×3=15 then 20-15=5 so Pat has the correct answer
The trick with this question is that you need more than one set of brackets.
4+5 × 2+3=9 ×5=45
All these rules that have been discussed in this article are important and it is not just for the case of your gcse maths exam but just in actual real life situations. Keep practising the questions, cover the solution, and see if you were able to gather the correct answer.
It is important to remember what the letters represent in BIDMAS or BODMAS. Always follow the rules carefully making sure that you are doing calculations in the correct sequence.