What is BODMAS And BIDMAS: Explained For Primary School Parents
BODMAS (or BIDMAS) is an acronym used to help students remember the order of operations. In this post we cover what it means, and provide you with some BODMAS questions and exercises you can use to help your KS2 child practise accurately carrying out BODMAS calculations.
What is BODMAS?
The BODMAS rule is an acronym to help children remember the order of mathematical operations – the correct order in which to solve maths problems. Some children also use it as a mnemonic (like Richard Of York Gave Battle In Vain is used to remember colours)
You may have also heard of it referred to as BIDMAS, but other than the one different letter the BODMAS or BIDMAS rule remains the same in its meaning.
“Mathematical operations” are what you do to the numbers given. The four main operations are:
- addition (+);
- subtraction (-);
- multiplication (x);
- and division (÷).
When presented with a number sentence containing more than one operation (such as 3 + 4 x 2) the operations cannot be completed from left to right, but instead in their order of “importance”, which is what BODMAS stands for.
BODMAS stands for:
“Orders” means square roots and indices (which you may know as square numbers, powers or exponents).
BIDMAS stands for:
Here “Indices” (square numbers, powers or exponents) are used instead of Orders.
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What does order of operations mean?
This is the order in which certain operations must be completed, from brackets first to addition and subtraction last.
It is important that division and multiplication are represented alongside each other as they are of equal importance (so must be completed from left to right, whichever appears first) – this is the same for addition and subtraction.
Below are some examples of BODMAS questions and answers children might see in schools. We’ve given you the right answer and at least one different answer to show you where children might go wrong.
BODMAS (BIDMAS) Questions and Answers
Question 1: 6 + 2 x 7
The correct answer is 20.
The multiplication must be completed first (2 x 7 = 14) and then the addition (6 + 14 = 20).
This may be commonly miscalculated as 56 by working from left to right (6 + 2 = 8, 8 x 7 = 56).
Question 2: 3 x (2 + 4) + 52
The correct answer is 43.
The BODMAS rule states we should calculate the Brackets first (2 + 4 = 6), then the Orders (52 = 25), then any Division or Multiplication (3 x 6 (the answer to the brackets) = 18), and finally any Addition or Subtraction (18 + 25 = 43).
Children can get the wrong answer of 35 by working from left to right.
Question 3: 5 – 2 + 6 ÷ 3
The correct answer is 5.
The division must be completed first (6 ÷ 3 = 2) which then leaves addition and subtraction; as both are of the same importance, we can then work from left to right. 5 – 2 + 2 (the answer to 6 ÷ 3) = 5.
This may be commonly miscalculated as either 3 by working from left to right, or as 1 by wrongly assuming that addition should be completed before subtraction.
When will my child learn about BODMAS in primary school?
BODMAS is taught in upper KS2 and often primary school children won’t come across the order of operations until Year 6
The national curriculum states that Year 6 pupils should be taught to use their knowledge of the order of operations to carry out calculations involving the four operations.
The non-statutory guidance advises that pupils explore the order of operations using brackets; for example, 2 + 1 x 3 = 5 and (2 + 1) x 3 = 9.
As a parent trying to support your child with order of operations questions you’ll find that most calculators and computers nowadays are sophisticated enough to complete calculations according to BODMAS. However it’s worth testing any calculator out just to be sure. There are also plenty of BODMAS calculators available online.
Practice KS2 BODMAS questions
1) 29 – 4 x 6 + 5 =
2) Write what the two missing numbers could be. (4 + ?) x ? = 100
Answer: 6 and 10 (4 + 6) x 10 = 100
3) Write the missing numbers to make these calculations correct.
a) 200 x ? – 200 = 200
b) (100 – ?) x 100 = 100
Answers: a) 2 b) 99
4) Write the correct sign >, < or = in each of the following
a) (10 + 5) – 9 [ ] (10 + 9) – 5
b) 3 x (4+5) [ ] (3 x 4) + 5
c) (10 x 4) / 2 [ ] 10 x (4 / 2)
a) (10 + 5) – 9 < (10 + 9) – 5
b) 3 x (4+5) > (3 x 4) + 5
c) (10 x 4) / 2 = 10 x (4 / 2)