# BIDMAS. BODMAS. Whatever. What is it?

BIDMAS. BODMAS. Whatever you call it, chances are you don’t remember it from school (or, as I maintain, never learned it in the first place).

It can, however, make a huge difference when you’re doing mixed calculations, and nowhere is this more visible currently than on social media.

You’re bound to have seen them: those maths problems using pictures of burgers and fries – or apples and bananas – or bottles and glasses of beer – where you have to work out the value of individual items, then solve the calculation at the bottom of the image.

As I was at first, you are probably gobsmacked by some of the answers people give: how can 5 + 1 x 10 come to 15? Surely that’s wrong, yet quite a few people are insisting that’s the right answer, even though you and many others make it 60.

And what the hell is that word some commenters seem to be shouting: “BIDMAS”?

BIDMAS is a mnemonic for remembering the order of operations in any mixed calculation: Brackets, Indicies, Division, Multiplication, Addition, Subtraction. (Apparently, we all learned it at school; I’m certain I must have been away that day, as were many others.)

Had the problem been written (5 + 1) x 10, then the answer would indeed be 60, but with the absence of brackets, we have to go with the next operation in the order of importance for that problem, and in this case it’s multiplication.

So, the correct order of operation is 1 x 10 (which = 10) then + 5 (which = 15).

So no – you don’t have to be a genius to solve these.

Here’s a link to my free video, in case you’d like to see how it’s done:

A more in-depth look at how BIDMAS/ BODMAS works will be on my full course of KS2 maths for parents, which I hope will be ready very soon.

Watch this space!

For many children, it’s important to visualise multiplication tables as they’re learning them.

I work with pupils of all ages and often find that gaps in knowledge are down to the same factors – usually something really basic but fundamental to the understanding of mathematical concepts.

As a year six teacher (many moons ago) I had a group of pupils – all intelligent, well-behaved children – who were stuck at level 3. I was expected to teach them how to find equivalent fractions, yet these children couldn’t master basic times tables.

Within the first few minutes of an extra after-school maths session, it became clear that these children did not know what times tables were. They could recite some of the simpler ones, such as 3 x 4, but didn’t realise until shown an array of counters that this could be represented by three rows of four or four rows of three.

We often assume that, just because children tell us the answer to something, they must also understand the concept behind it. This really isn’t always the case. And without that understanding, these children were unable to make links between multiplication, division, fractions, and other essential mathematical concepts.

Now I’m working with GCSE pupils who are struggling with maths, and it’s always the same problem: a lack of basic number understanding, which means they take longer to work out calculations. A sixteen-year-old who has to count on fingers to work out 7 x 6 is going to take a lot longer to answer questions in an exam than someone who already knows the answer and who can then instantly apply that information to working out the value of x when 60x = 4200, or when 6x = 4.2. Even in the calculator exam, it helps if you don’t have to use the calculator for every single calculation involved in a complex problem: this saves time and minimises the probability of making an error as a result of pressing the wrong calculator buttons.

The older the pupil, the more difficult it is to get them to learn their basic number facts: really, you just have to persuade them of the value of this, and that’s no easy task.

Getting younger children to learn number facts can be fun, especially when using games, but practice must be regular so they don’t forget.

And keeping on top of this learning is essential when children leave primary school: I’ve lost count of the number of secondary pupils who say ‘I knew that in primary school but I’ve forgotten it now.’

I’m not a great fan of rote learning, but I do believe that learning off-by-heart facts such as doubling and halving, number bonds and multiplication tables are essential. Learning these basics saves time and opens doors to all kinds of more challenging number concepts.

It’s essential that we make sure children actually understand what it is they are learning, as well as why it’s useful, otherwise they will be unable to make necessary links and will struggle more as the level of maths progresses.

It’s a sad fact that schools do not have enough time to ensure every child really understands rather than just remembers facts; as parents, we need to make sure our children are equipped with the knowledge and understanding they need to retain their confidence with maths. I hope my videos will help you with that.

Kathy

The Cambridge Tutor