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Bidmas

Discussion in 'Mathematics' started by Deirds, Jun 20, 2012.

  1. Deirds

    Deirds Senior commenter

    Hi

    Parent looking for help here.
    My Yr 8 son was doing MyMaths and I was helping him with something he was getting wrong (6*x^2 not being the same as (6*x)^2. )
    I vaguely remembered last year's teacher saying he needed to work on Bidmas. It was Bodmas when I was at school. Would I be correct in thinking I is for Indices? Do they not need to worry aboit O for Of any more? Do the other letters still stand for Brackets, Division,Mulitiplication, Addition, Subtraction?

    Thanks
     
  2. PaulDG

    PaulDG Occasional commenter

    Welcome... And you've highlighted why many of us are uncomfortable with teaching "BIDMAS/BODMAS/PEMDAS"...

    (Which is that kids remember the word but forget what it means, why they were taught it and that every question is a BIDMAS question!)

    Brackets, Indices, Multiplication/Division (equal priorities), Addition/Subtraction (also equal priorities).

    Or

    Brackets, Order, Multiplication/Division (equal priorities), Addition/Subtraction (also equal priorities).

    Or

    Parenthesis, Exponentiation, Multiplication/Division (equal priorities), Addition/Subtraction (also equal priorities).

    They're all equivalent mnemonics that are intended to help you remember how to deal with the fact that mathematical notation, unlike written English, is minimalist.
     
  3. I use the O for 'other' - covers trig functions etc as well then.
     
  4. Deirds

    Deirds Senior commenter

    Thanks for the replies. I will admit that until I got to multiplication I had misremembered D is for Decimal. I corrected it, but it was nearly 40years ago...and I don't think we used it much..
     
  5. By coincidence, I was leafing through a revision guide from a well known publisher which said that the O stood for 'over'. Not sure what that is about!
     
  6. markuss

    markuss Occasional commenter

    I'm no mathematician! I thought the "O" was for "operations". Shows how much I know.
     
  7. i'd go for 'other'as well
    but it is a pain - why not just put scads of brackets in - how much extra ink would that us?
    i tell pupils it's like putting words in the correct grammatical order in a sentence
    but it isn't - it's like talking in yoda-speak with a set of interprative rules
    to copy cybola - florapost - in a bad mood tonight
     
  8. PaulDG

    PaulDG Occasional commenter

    You really want to have to write:

    (6x) + (3y) - (2z) ??
     
  9. now - that's just being silly
    are you someone in my y5 group under an assumed name?
     
  10. Piranha

    Piranha Star commenter

    I don't think it works for Trig functions. Sin 2x is usually taken to mean sin (2*x) rather than (sin 2)*x which would be the case if the sine function was done before multiplication.

     
  11. Yes I know, but a function inside another function has invisible brackets like one function divided by another.
     

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