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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 orionmoo)
    I'm more concerned with the lack of consistency on the way the two different calculators are programmed - the Standard calculator being one most likely used by those with a lack of knowledge on how they should be using parentheses to calculate sums in the correct procedure...
    It's not really a problem if you do some working out before you bang things into the calculator. It's fairly well-understood that if you're going to use a calculator to calculate a long expression of things then you need to worry about what's in brackets etc first. That is, if \circ_i are operations and n_i are numbers then plugging [n_1] [\circ_1] [n_2] [\circ_2] \cdots [\circ_k] [n_k] will give you (\cdots ((n_1 \circ_1 n_2) \circ_2 n_3) \circ_3 \cdots \circ_{k-2} n_{k-1}) \circ_{k-1} n_k, no matter what the operations are.

    It's not much good because then it would mean that 3x+4y means the same as (3x+4)y, but it's fine if you're just adding a few things together.
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    (Original post by nuodai)
    What's more amusing is how wound up some people are getting about this. I mean, typing in capital letters?! This extreme level of rage must be calmed!
    Agreed. Although to me it feels like the debate is between those who have gone through their life enjoying maths and considering it the one concrete academic line, who end up arguing with the people who either like to wind other people up or like to disprove basic axioms and hypothesise (ie the 'philosophers').

    Many great mathematicians have pointed out such inconsistencies in mathematical logic and I doubt they'll be the last, but has anyone actually found a way to change it? Perhaps, but getting it out to the public would require a complete overhaul of the education and finance system that we currently use (I'd assume... I'm no expert).

    Unless there's a point where the value of 48/2(9+3) will make the world dive headfirst into another recession, maths is probably fine the way it is... with little ambiguities which cause people to post outrageously on the internet.

    (lol I have an image of the new Batman movie where the Joker puts a bomb in Gotham and says that the answer to disarming it is the simplified version of 48/2(9+3)...)
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    (Original post by nuodai)
    If the problem was 48/(2(9+3)) then there would be no ambiguity and everything you say would be correct, but that's not what the problem is. It's the lack of brackets (be it around the denominator or around the 48/2) which creates the ambiguity. The bit in bold is the rule you've made up; you can either consider 2(9+3) as an unbreakable entity (giving 2), or \frac{48}{2}(9+3) as an unbreakable entity (giving 288), and it's not clear from the notation which it is unless some more brackets are inserted. You've arbitrarily chosen to insert them around (2(9+3)), whereas some arbitrarily choose to insert them around (48/2); there is no rule which says which you have to do.

    So again I repeat: nothing to do with distributivity.

    Consider the working out for the answer 288:
    48/2(9+3)
    =(48/2) x (9+3)
    =24 x (9+3)
    =24 x 12
    =288

    The second step: (48/2) x (9+3) cannot be the correct working out because it implies that the original question was 48(9+3)/2 which clearly, it wasn't.
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    (Original post by timiop2008)
    The second step: (48/2) x (9+3) cannot be the correct working out because it implies that the original question was 48(9+3)/2 which clearly, it wasn't.
    You've just discovered how the whole debate started -- contrary to what you say, it's not clear at all that the 9+3 is meant to be in the denominator, and if you're talking about distributivity then I'd hope you're at the level of maths where you know that "it looks like it should/shouldn't be" isn't a good enough argument to prove something you say is correct. And indeed, it's not clear. Common sense would indicate that 9+3 is indeed on the denominator, but a tight following of "BIDMAS and then left-to-right" would indicate that it's on the numerator; neither is 'more correct' than the other, hence ambiguity.
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    (Original post by timiop2008)
    Consider the working out for the answer 288:
    48/2(9+3)
    =(48/2) x (9+3)
    =24 x (9+3)
    =24 x 12
    =288

    The second step: (48/2) x (9+3) cannot be the correct working out because it implies that the original question was 48(9+3)/2 which clearly, it wasn't.
    48/2(9+3), without adding any brackets here or there, would become 48/2(12) then 24(12) then 288 using BODMAS as DIVISION COMES FIRST (in BODMAS, though they're equally weighted, in which case you can simply do 48/2 first since we read from left to right)

    Why do you think we have to make it (48/2) x (9+3) in order to get 288?
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    (Original post by Joinedup)
    Google says 288 and google knows everything http://www.google.co.uk/#hl=en&xhr=t...07647f54fc789f
    i don't believe you googled it. THAT is so awesome! HAHAHAHAHA!

    I'm shocked the first few posters thought it was 2, and even more shocked the guy who first proposed the current answer of 288 was so harshly neg repped! What a bunch of morons.
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    (Original post by nuodai)
    Common sense would indicate that 9+3 is indeed on the denominator, but a tight following of "BIDMAS and then left-to-right" would indicate that it's on the numerator; neither is 'more correct' than the other, hence ambiguity.
    Why should common sense be considered an equivalent argument against BIDMAS?
    -edit-
    I think BIDMAS is "more correct" (if that wasn't obvious before)
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    (Original post by SsEe)
    Brackets first:
    48 / 2 * 12
    Then do multiplication and division from left to right.
    48 / 2 = 24.
    24 * 12 = 288

    That's actually really odd because about 2 hours ago I was talking to someone about mental arithmetic and the question he randomly picked was 24 * 12.
    It's mathematical judgement day :eek:
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    (Original post by Sovietpride)
    2.

    BIDMAS

    So
    48/2(12) (or 48/(18+6)
    48/24
    2

    That's my 2 cents.

    Edit: No pun intended.
    You mean BODMAS?
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    (Original post by planetconwy1)
    You mean BODMAS?
    Does it matter?
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    (Original post by ada1023)
    Why should common sense be considered an equivalent argument against BIDMAS?
    Because notation serves to make our lives easier, not the other way round. But that said, even BIDMAS doesn't make it clear, because when you have a fraction, the top and bottom are each implicitly surrounded by brackets. You can't do this problem even using BIDMAS without agreeing first whether the (9+3) is on the numerator or denominator.

    (Original post by planetconwy1)
    You mean BODMAS?
    They're the same thing. In fact, Americans call it PEMDAS (parentheses-exponents-multiplication-division-addition-subtraction).
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    (Original post by wanderlust.xx)
    Does it matter?
    No I suppose not!
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    (Original post by andrewmc96)
    Multiplication and division are equally-weighted so you work from left to right (after the brackets and indices have been dealt with) - one has no precedence over the other.
    What textbook says this? I challenge you to cite this claim and show me the evidence. BODMAS states division has precedence over multiplication....
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    (Original post by wanderlust.xx)
    Does it matter?
    Indeed, I would be more concerned about the fact that the pun clearly was intended.

    And that they applied BODMAS/BIDMAS wrong...
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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....
    I'd like you to find me a textbook that says the contrary. If Wikipedia can't convince you, then I hope its references/external links can. [It is indeed true that division and multiplication are given the same preference, as are addition and subtraction.]
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    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.
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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....
    nope, they are equally weighted
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    (Original post by ArtemisRose)
    I would say 2.

    We were taught BOMDAS and also BODMAS.

    In my maths class we were told it makes no difference.
    Yet here it is, making a massive difference.
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    (Original post by nuodai)
    Because notation serves to make our lives easier, not the other way round. But that said, even BIDMAS doesn't make it clear, because when you have a fraction, the top and bottom are each implicitly surrounded by brackets. You can't do this problem even using BIDMAS without agreeing first whether the (9+3) is on the numerator or denominator.
    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.
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    This thread is frustrating, it should of had 1 reply of (2) and that should of been it :/
 
 
 
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