KS2 maths question

[FiveStoryFire]

Multiply the sum of 16 and 9 by 8.

What is the order of operations please?

[DadDadDad]

I think that can only be interpreted as multiply (the sum of 16 and 9) by 8 ie
(16 + 9) x 8

so you add the 16 and 9 first.

[DadDadDad]

What other order is even possible?

[Fairenuff]

I agree 16+9 first
Then multiply by 8

[PattiStanger]

If that's the exact question it's very clear that you have to add the numbers together then multiply. Is that the actual wording I'd expect a year 6 child to know what to do.

[FiveStoryFire]

Ok. Thank you. I just thought multiplication always comes before addition though?

So 16 + 9 x 8 = 88?

[DadDadDad]

But the question wasn't 16+9x8. It was a word problem so you have to translate it to a mathematical expression including the use of brackets to group things which language groups using grammar.

So if I say what's larger, the sum of 10 and 3 or the sum of 11 and 5, the "of...and" groups things together: sum of 10 and 3 is (10 + 3), the sum of 11 and 5 is (11+5).

Or the other way to look at it is "multiply SOMETHING by SOMETHING" means you need to work out the SOMETHINGs first. The first SOMETHING in your OP is "sum of 8 and 9"

[Gizlotsmum]

Normally it is multiplication first but it asks you to multiply the sum of 16 and 9 by 8 so it adds brackets which makes that the first thing you do.

[DadDadDad]

Or one last way to look at it: if I say "Deliver the letter and the newspaper by hand" the overall structure is "Deliver X by hand", so I have to put the X together (letter and newspaper) then deliver the lot. (don't push this example too far but hopefully it shows it's about sentence structure not BIDMAS).

[caughtinanet]

Maybe you're making it harder than it needs to be OP, you don't need to know BODMAS (or whatever the right order is) to solve this one as the question clearly tells you what to do.

[DadDadDad]

caught - you are right, but it is questions like this that expose children's (and their parents') misunderstanding. A child might say "teacher says do brackets first - well there are no brackets, then multiply and divide, so I multiply 16 by 8 then... , add... the 9...?"

So this creates a moment to learn what the scope of BIDMAS is.

[grumiosmum]

200. It's easy.

[grumiosmum]

The sum of 16 and 9 is 25.

Multiply that by 8. It is 200.

[DadDadDad]

grumiosmum - I think answers like that are unhelpful and contribute to children (and their parents) losing confidence ("if it's easy, why can't I do it? I must be thick").

Most of us know it's 200, but that's not what the OP is asking.

[dementedpixie]

It tells you to add first and then multiply so add 16 and 9 first before multiplying by 8

[grumiosmum]

Sorry Dad3 & OP.

I did double Maths A-Level (albeit a long time ago) so of course I found it quite easy. I appreciate that others wouldn't - and they are probably much better at things that I can't do.

[dementedpixie]

Multiplication would normally come first if you hadn't been told to add the 2 numbers together first before multiplying that answer

[caughtinanet]

If a child is thinking like that Daddaddad then the teaching would appear to be at fault, are they not taught that a question in words shouldn't be approached in the same way as one purely with numbers and symbols.

OP - is your child in year 6? Is this a revision type question? Good that you've found out now that she/he isn't clear on the basics of identifying what the question is asking in plenty of time for the teacher to go over before the test

[caughtinanet]

Dementedpixie - I can't see how you would word a question where the multiplication should be done first, what would be an example? Having a mental blank.

[grumiosmum]

Add 6 to the product of 3 and 5?

Does product mean multiply? I've got menopausal brain.

[grumiosmum]

The answer is 21. If I've worded it correctly.

[dementedpixie]

I meant more that if you wrote down 16 + 9 x 8 then you would multiply 9 x8 first before adding to 16

[caughtinanet]

Sorry, I wasn't as clear as I should have been, I'm trying to think of a word question that would mean you needed to apply BIDMAS ie it wouldn't be obvious what to do. I have too long a day at work brain and can't think of one

[DadDadDad]

If a child is thinking like that Daddaddad then the teaching would appear to be at fault,

I think that's a bit of a reductive view of teaching. Teaching can focus on one skill (eg order of operations) so that is taught well, but won't necessarily address all misconceptions or limitations in one go. By then exposing pupils other problems, we can discover those misconceptions. So, good teaching will vary the types of questions that are asked to help pupils see the pitfalls and deepen their understanding.

[caughtinanet]

I get that dementedpixie but this isn't a question like that, I don't know what you call it when the whole question is in words rather than numbers and symbols, I can't think of an instance when it wouldn't be straightforward with only words

[caughtinanet]

I'm not a teacher but would expect that you'd start with the questions like the OP's, make sure the children understood what was needed then move onto the number equivalent where you need a prescribed order of doing things and ensure that the first thing to do is to identify what sort of problem you're being asked to answer.

As a parent I'd be concerned if my child wasn't clear on what they were being asked, not so much if they didn't understand BIDMAS but that they thought that it was needed in a word question (is there a technical name?)