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48÷2(9+3) = ? watch

  • View Poll Results: 48/2(9+3)
    2
    117
    52.47%
    288
    106
    47.53%

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    (Original post by CameraGirl)
    yes, including me! i have stated how it is slightly ambiguous and not entirely clear, if you bothered reading my earlier posts, but how the best way to go about it, and the more mathematically correct way, gives the answer of 2.
    even using BIDMAS, the 2 is part of the brackets, if the coefficient of (9+3) were (48/2) then 48/2 would have been put in brackets by whoever wrote the question, as they would have spotted the ambiguity and rewritten it, however had they intended it to be 48/(2*(9+3)), then they may not have spotted the ambiguity within their intent.

    try thinking about it from the point of view of the person who set the question, too. they would have been more likely to notice it was in bad format, had they intended it to be (48/2)(9+3).

    if it were algebra instead, you wouldnt still be debating it, as first instinct would be to expand out the brackets!

    BODMAS could also be interpreted as: brackets first - expand them out. although yes there is ambiguity with what the coefficient is. gah this is so frustrating!
    Yes, I think the person who wrote the question probably intended it to be written in such a format as to give the answer to be 2.

    However, in the ambiguous nature the question is currently written in, we cannot speculate where the 2 should go, so we just have to work left to right. Which gives 288.

    Obviously this will just go round in circles lol.

    Basically, loads of people are adding in "fake brackets" to include the 2. I'm not, I'm saying there are no brackets either to enclose the (48/2) or the (2(9+3)), so in the absence of such brackets, we just work left to right.
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    (Original post by RollerBall)
    48÷2(9+3)
    48÷2(12)
    48÷24
    = 2

    Don't be herping the derp. It's 2. Endo storo. Just because you've calculated what's in the brackets doesn't mean the bracket has gone away.
    The brackets have nothing to do with that step. 2(12) is two multiplied with twelve; just because I put brackets around the twelve like so (twelve) doesn't necessarily mean I need to everyone that's related to the bracket first, although granted, that's how I/most would see it.

    (Original post by Zap Brannigan)
    Yet here it is, making a massive difference.
    Holy crap it's Zap Brannigan. All that's left is getting Chuck Norris in here and awaiting the verification of Godwin's Law! :awesome:

    (Original post by Jonty99)
    Obviously this will just go round in circles lol.
    Yes but it's quite an enlightening little conundrum.
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    (Original post by blue_shift86)
    What textbook says this? I challenge you to cite this claim and show me the evidence. BODMAS states division has precedence over multiplication....
    No, you're wrong. Multiplication and Division are on the same level.
    http://www.mathsisfun.com/operation-order-pemdas.html
    http://www.ehow.com/how_4449191_solv...ng-pemdas.html
    http://www.bbc.co.uk/schools/ks3bite.../revise2.shtml
    http://www.cimt.plymouth.ac.uk/proje...i4/bk8_4i3.htm
    http://www.channel4.com/programmes/d...t-count-bodmas
    http://www.purplemath.com/modules/orderops.htm
    http://www.math.com/school/subject2/.../S2U1L2GL.html

    Need I add any more???
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    48 / 2 (9 + 3) .... 9+3=12

    48 / 2 * 12 ... 48/2=24

    24 * 12 ... 24*12=288

    288

    (equivalent)

    even wolfram|alpha says so.
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    (Original post by RollerBall)
    48÷2(9+3)
    48÷2(12)
    48÷24
    = 2

    Don't be herping the derp. It's 2. Endo storo. Just because you've calculated what's in the brackets doesn't mean the bracket has gone away.
    The 2 isn't in brackets.
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    (Original post by ada1023)
    Well if we knew whether (9+3) was a numerator or denominator there would be no reason to use BIDMAS, we would simply divide the product of the numerator by the product of the denominator. The only reason we would use BIDMAS is for situations like this, where we must determine which functions to execute first. I agree that we should follow notation, but when the notation is ambiguous like in this example, using BIDMAS would seem necessary, and the only solution to overcome said ambiguity.
    No, you use BIDMAS so that when you write something like 3×2+8÷2 you get 10 rather than 7, 15 or 18 (which are all things you can get by not following BIDMAS). However, when I write 2^3x it's fairly clear, to me at least, that I mean 2^{3x}, but applying BIDMAS would tell me it's equal to 8x.

    BIDMAS isn't there to make ambiguous statements unambiguous; it's there to give you a framework with which to represent basic operations in mathematical notation. If you come across something which is ambiguous, you don't apply a contrived interpretation of BIDMAS to it (like people are doing here); instead you work out what it's supposed to be and fix it. But in this case we have no context other than "what is this", so we can't work out what it's supposed to be, so we can't fix it.

    In this case, BIDMAS falls at the "brackets" bit, because it's not clear whether there should be a bracket around 2(9+3) or around 48/2. Regardless of what you do, there is an implicit bracket around one or the other, but it's not clear which, so it's ambiguous.
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    I really wanted it to be 2, as this is what i just instinctively thought; but i typed it into my calculator exactly and got 288.
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    how on earth can it not be 2?

    the (9+3) can be thought of as a single number, 12, because it's in brackets.

    and then the 2 x (12) or 48=2 can go either way
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    Re: 48÷2(9+3) = ?

    I say 288 because BODMAS so...
    brackets first 48÷2(12)
    then division... 24(12)
    24 x 12 = 288

    I might be wrong...
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    (Original post by nuodai)
    No, you use BIDMAS so that when you write something like 3×2+8÷2 you get 10 rather than 7, 15 or 18 (which are all things you can get by not following BIDMAS). However, when I write 2^3x it's fairly clear, to me at least, that I mean 2^{3x}, but applying BIDMAS would tell me it's equal to 8x.

    BIDMAS isn't there to make ambiguous statements unambiguous; it's there to give you a framework with which to represent basic operations in mathematical notation. If you come across something which is ambiguous, you don't apply a contrived interpretation of BIDMAS to it (like people are doing here); instead you work out what it's supposed to be and fix it. But in this case we have no context other than "what is this", so we can't work out what it's supposed to be, so we can't fix it.

    In this case, BIDMAS falls at the "brackets" bit, because it's not clear whether there should be a bracket around 2(9+3) or around 48/2. Regardless of what you do, there is an implicit bracket around one or the other, but it's not clear which, so it's ambiguous.
    Nice one, you just convinced me. Also is there a tutorial anywhere here on how to use latex?
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    (Original post by ada1023)
    Nice one, you just convinced me. Also is there a tutorial anywhere here on how to use latex?
    Yup: http://www.thestudentroom.co.uk/wiki/LaTex
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    It's 288. And I can't believe this has 29 pages.

    Going back to the original equation, using the law of distributivity of numbers means we can rewrite this as:
    9*(48/2)+3*(24/2)

    But really, it's just a poorly written equation. But I'd go with implied brackets around 48/2
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    You know what's confusing...

    The person who said "288" on the first page of this thread got neg repped a ridiculous amount, and yet the poll on the other thread shows 50% of people think it's 288.
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    Use Wolfram Alpha you can't get it wrong then.
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    It's definitely 288 and Microsoft Mathematics seems to agree with me.

    Picture 48/2 as a fraction, then I think you can see where we're coming from.

    You work from left to right!
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    (Original post by DanielleT192)
    Or maybe the questioner is an idiot who should've made it clearer? Lets just come to the conclusion that some people will obtain an answer of 2 or 288 but the questioner should've displayed the question with more clarity. I still would take the answer to be 2.
    fag - it's 288 - go back to pre gcse studies girl.
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    It's 288.
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    Can someone answer this question of mine, please?

    Would you not agree, that with the question as written we can't assume the 2 to be part of the denominator, so surely we just have to calculate it left to right, as there's nothing else we can do?

    I'm baffled at people saying 2 here. They're putting in an extra bracket. 288 doesn't require an extra bracket, it's what you get when you go from left to right.
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    crappest sources ever. They've probably been written by noobs who barely got through GCSE's and decided to be a popular kiddy maths writers. They should be banned from teaching - they're teaching kids incorrect things! I maintain my stand: show me a credible source - only one of those sources supports what you say about multiplication and division having equal precedence, and even that seems to have been written by some GCSE failing noob.
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    (Original post by blue_shift86)
    crappest sources ever. They've probably been written by noobs who barely got through GCSE's and decided to be a popular kiddy maths writers. They should be banned from teaching - they're teaching kids incorrect things! I maintain my stand: show me a credible source - only one of those sources supports what you say about multiplication and division having equal precedence, and even that seems to have been written by some GCSE failing noob.
    lol you must be trolling.

    Division and multiplication are equal in preference.
 
 
 

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