to think that BODMAS/BIDMAS is a pile of pish devised to keeps children busy?

[duchesse]

And designed to palliate poor notation.

I see about 6 threads a week from parents baffled by their children's homework. It puts me in a rage. If I'd written such poorly punctuated sums out as the ones these beleaguered parents are having to deal with when I was back at school I'd have been in detention every week. Yet these are inexplicably set as homework.

Can anybody tell me if learning these stupid rules (rather than learning proper notation including brackets from the get-go) can actually help children at all in any way? Or is it, as DH suspects, merely a nifty way of generating activities that can easily be marked? DH has an Oxbridge degree in maths and Phd in phsyics btw and also cannot see why the feck this is being taught.

Casimir you still need to know what you are writing is correct.

As for the 'you don't need this for xyz' argument, when was the last time you needed year 7 history at the till?

The whole point of comprehensive education is that it gives all a base level of education that people can choose to expand on. Not everyone will work on a till, likewise not everyone is a physicist.

Ah thanks Penelope I was just about to post that I learnt it a PEMDAS 30 yrs ago (in the us) and was thinking I've had it wrong all these years.

It's not the equivalent of handwriting though, Casimir. You still need to know if/where to put brackets to type an equation or expression that says what you mean it to say. It's the equivalent of getting the letters and words in the right order which you need to do whether on a computer or not. Except there's no spell check to fall back on. You still need to know it to be able to read the equation.

Surprised anyone with a degree in physics from anywhere doesn't see the point in bodmas. Physics is littered with equations that use it. More likely it's so ingrained he does use it without even knowing he does.

I'm still baffled as to what proper notation is supposed to look like? Please can someone enlighten me??

YABU because (as several people have pointed out) you are wrong. A formula without unnecessary brackets isn't poorly written or wrong. In fact inserting redundant brackets would usually be an odd thing to do.

YABU.

Most computer languages assume BODMAS. If your DCs are ever going to do any sort of coding or computer programming then they'll need to know it. Likewise most calculators do too.

Let's hope your Oxbridge educated husband doesn't want to go into teaching anytime soon!

It is important as others have said - it is not a filler to 'keep children amused' and is something that as others have said form the basis for a lot of other skills, coding, spreadsheets, higher level calculations using algebra - although that last one will probably get a response of 'when do I ever use algebra'

I had never heard of BODMAS til my two went to school.

When it comes to computing it's good to know BODMAS - stack evaluation, reverse polish notation, all sorts of stuff builds or directly uses the same rules, it's fundamental to how computers work.

Sure, some people might never use algebra or this stuff, but plenty of people will, and general knowledge can only be a good thing surely!

Disagree, mostly. Knowing the correct order of operations is an essential part of being able to understand and use mathematical expressions clearly. You and your DH may take it for granted that 2x+5 means that you multiply the x by 2 and then add 5, rather than multiplying all of x+5 by 2, but it's only a rule of the language, and it has to be taught. It would also be rather clumsy to have to write (2x) + 5 instead.

However, I do agree that sometimes expressions would be clearer with brackets, and that could be taught too. Plus, as others have said, it actually doesn't matter at all whether your multiply or divide first, and whether you add or subtract first, and that should be made clear too.

(I teach Economic theory at University level and both teach and use mathematics all the time)

duchesse, have you not heard about the national bracket shortage? Shame on you.

OP I can relate to the frustration but really, Maths is like another language. If you're looking at the level of equations involved in a Cambridge Maths degree, then there is much more complex grammar involved.

I can see comparisons with learning German and how word order, spelling and articles can be affected by the case, tense and various reforms.

this is currently doing the rounds on linkedin

1+1+1+1+1+1+1+1+1+1+1+1 x 0 +1 =

i think its 12? or 1. Anyone know?

to follow the thread though this IS badly written. if there were brackets it would be simpler as (1+1+1+1+1+1+1+1+1+1+1+1) x 0 +1 =

then it surely would be 1.

At a guess, I think Casimir was being facetious. Can I just say thanks to the posters who explained though? I managed to get a GCSE in maths without understanding most of it, and one of the things MN has done for me is highlight huge gaps in my knowledge that should be simple foundation level maths. This thread has given me the final push I needed to sign up to do an adult numeracy course so that when DS gets to all this, I can understand and maybe even help him!

Emkana. Take 7 x 2 + 5 x 2. This is perfectly correct notation for a calculation where you work out the 7x2 and 5x2 first and then add the two answers.

The OP is trying to argue that this is poorly written and should be written (7 x 2) + (5 x 2). It could be written that way but the brackets are unnecessary because we have an agreed way of 'reading' expressions like this, which is that you always do the multiplication and division first before you do the addition and subtraction.

If you wanted to do the calculation from left to right in the order it is written you would need to add some brackets to tell you that. (7 x 2 + 5) x 2 would probably do it.

If you were going to add brackets to that sum you would put them around the multiplication part, as that is the part you should be doing first.

1+1+1+1+1+1+1+1+1+1+1+(1 x 0) +1 =

so your answer is actually 12

You can't just put brackets where you think they would make the sum look better, it changes the whole set up of the sum.

It is 12. You do the 1x0 first so it becomes

1+1+1+1+1+1+1+1+1+1+1+0+1 =

If you put brackets in as you have the answer would be 1. But by the rules used for equations the second equation in your post is not the same as the first one. Multiplication comes first in this equation then addition. That's exactly what BIDMAS/BODMAS is all about.

Elysianfields, that is the whole point of Bodmas! As it's written it's 12. If it had the brackets you put in it would be 1. Two totally different "sentences", not one poorly written one!

Elysianfields, it's 12.

If you put the brackets in like you have then it is 1.

Although, hundreds of people are going to be here in a minute telling you is is 1 because anything x0 is 0.

Thanks for the explanation Rafals.

The only time you would need to add brackets to 7 x 2 + 5 x 2 is when you want to add 2 to 5 before you multiply 7 x (2 + 5) x 2.

Your answer then changes from 24 to 98. Quite a difference, and will completely invalidate any further sums using the answer.

I have never heard of this.

I thought you were talking about IKEA products.

Not sure about that. (7x2+5)x2 gives 38 which is different to 24 and 98. Put the brackets in a different place again and you can get 84 too.

Sorry, you're correct. My mistake for not checking all bracket placings

Still, that certainly highlights the importance of following the BIDMAS rule.