What is BODMAS?

This blog is dedicated to explaining the much-misunderstood maths acronym BODMAS (or you might know it as BIDMAS). It’s something that your child will come across towards the end of Key Stage Two and it tells you the order to do each part of a complicated calculation like this: 12 × (4 – 2)² ÷ 3*. There is a right way and it’s well worth understanding what it is to avoid getting in a pickle over maths homework.

(*The answer is 16.)
 

What does BODMAS stand for?

Let’s start with the basics. Each letter in BODMAS stands for a mathematical operation. There’s no need to page the surgeon though — in maths, an operation is just something we do to numbers to get a new value, like adding them together. The letters of BODMAS stand for Brackets, Orders of powers/roots, Division, Multiplication, Addition and Subtraction. Most of these you’ll be very familiar with, but here’s what the trickier two mean:

Brackets — do any calculations in brackets, e.g. (2 + 9)
Orders of powers/roots — square or cube the number, or find its square or cube root, e.g. 5²
 

What does BIDMAS stand for?

If you’re using BIDMAS instead of BODMAS, the I stands for Indices, which is basically the same thing as ‘orders of powers/roots’. Everything else about BODMAS still applies.
 

How do you use the BODMAS rule?

There’s no real trick to it — the order of the letters in BODMAS gives you the order to do each operation in. In a calculation with more than one operation, you follow BODMAS rather than working from left to right.

However, a common misconception is that division always come before multiplication. This isn’t true. Technically, you do division and multiplication at the same time (whoa now), but in practice this just means doing them from left to right once they’re the only operations left. The same is true if you only have addition and subtraction left to do. Here’s the real order to do operations in:

Who knows, perhaps in an alternate universe somewhere, there are Year 6 pupils learning BOMDAS or BIDAMS instead…

It’s less confusing than it sounds, honest — take a look at the examples below.
 

BODMAS examples

This is a fairly straight-forward example. It contains addition and multiplication — you just need to use BODMAS to decide which to do first (spoiler alert: it’s multiplication):

6 + 2 × 5    BODMAS
= 6 + 10     BODMAS
= 16

This next example contains brackets and division. All you have to do is work out the calculation in the brackets first, then you’re left with a division:

4 ÷ (8 – 6)   BODMAS
= 4 ÷ 2         BODMAS
= 2

Now things are heating up — this example has two lots of orders (or indices). Do those first and then you’re left with a multiplication and a subtraction — BODMAS tells you to do the multiplication before the subtraction:

100 − 3² × 2³      BODMAS
= 100 – 9 × 2³    BODMAS
= 100 – 9 × 8     BODMAS
= 100 – 72         BODMAS
= 28
 

BODMAS Top Tips

Despite everything we’ve been through, BODMAS can still be confusing. Here are some top tips for you and your child to make using it that little bit simpler:

1. Take it step-by-step. Like the examples above, write out a line of working for each operation you do and you’ll be less likely to make a mistake. And if you do make a mistake, you’ll find it easier to spot where you made it.
2. The maths should be simple. If you get to a step that you or your child can’t easily do (for example, one with a decimal answer, like 2 ÷ 3, chances are you’ve gone wrong somewhere. Always bear in mind that the individual steps in most BODMAS questions at Year 6 should be answerable without a calculator. Try checking your working for any mistakes.
3. Many calculators follow BODMAS. If you want to check whether an answer is correct, use a calculator. Lots of calculators (including those online or on your phone) follow the rules of BODMAS — you should be fine as long as you can type in the whole calculation in one go.

BODMAS Worksheets and PowerPoints

Last but not least, CGP+ has some excellent Year 6 BODMAS resources — get started with this worksheet and PowerPoint that are perfect for getting to grips with the order of operations and practising BODMAS calculations.

Hope this helps — at the very least, you’ll be able to tackle those annoying ‘99% of people get this wrong’ problems on social media. Welcome to the 1%.