• Kaltenzahn@eviltoast.org
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    1 year ago

    I’m really bad at math (due to my severe dyscalculia), but I learned back in school that you should prioritize multiplication over addition. It means: First, you do 2x4 which gives you 8, then you add 2 to that, resulting in 10.

    Therefore: 2x4=8+2=10

  • Rentlar@beehaw.org
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    1 year ago

    Since the correct mathematical answer isn’t one of the options, the people picking the other options are representing a real resistance to the order of mathematical logic that binds us.

    The real answer is 14 because I’m 14 and this is deep.

      • float@feddit.de
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        1 year ago

        For me it’s 13 because it’s the “wrongest” one. Every single number in the term is even so you’d expect people to at least choose something that is even, too. Not only is 13 odd, it’s a friggin prime…

  • nLuLukna @sh.itjust.works
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    1 year ago

    Pemdas isn’t as arbitrary as people in this thread think it is.

    I love maths, and I’m going to butcher any attempt to explain why pemdas isnt totally random. But you can look it up if you wanna know more I guess

    Besides no one ever uses that notation - by the time you learn about quadratics, you leave multiplication symbols out of the equation entirely and much of the notation changes shape, with division exclusively being expressed as negative powers or fractions.

    At that point you aren’t going to make mistakes, since each hyperlevel uses a different style of notation. Pemdas is used to teach 4 year olds, and it’s fucking dumb. What happens with a log, or sine function. Don’t even get me started on integrals and derivatives.

    Pemdas is shit, but not because it’s abirtary. In fact it’s shit because it’s a shithole acyromn

    • Uphillbothways@lemmy.world
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      1 year ago

      Pemdas is mostly just factoring, kinda. That’s how you should think of it.

      2x4 is really 2+2+2+2.

      That first 2+(anything else) can’t be acted/operated upon until you’ve resolved more nested operations down to a comparable level.

      That’s it. It’s not arbitrary. It’s not magic. It’s just doing similar actions at the same time in a meaningful way. It’s just factoring the activities.

      • Kogasa@programming.dev
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        1 year ago

        It is, in fact, completely arbitrary. There is no reason why we should read 1+2*3 as 1 + (2*3) instead of (1 + 2) * 3 except that it is conventional and having a convention facilitates communication. No, it has nothing to do with set theory or mathematical foundations. It is literally just a notational convention, and not the only one that is still currently used.

        Edit: I literally have an MSc in math, but good to see Lemmy is just as much on board with the Dunning-Kruger effect as Reddit.

        • Uphillbothways@lemmy.world
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          1 year ago

          If you don’t accept adding and subtracting numbers as allowed mathematical transactions, multiplication doesn’t make sense at all. It isn’t arbitrary. It’s fundamental basic accounting.

          • Kogasa@programming.dev
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            1 year ago

            What you just said is at best irrelevant and at worst meaningless. No, the fact that multiplication is defined in terms of addition does not mean that it is required or natural to evaluate multiplication before addition when parsing a mathematical expression. The latter is a purely syntactic convention. It is arbitrary. It isn’t “accounting.”

        • nLuLukna @sh.itjust.works
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          1 year ago

          Yeah I haven no idea what I was saying when I said that, I’ve edited my comment a bit.

          On that note though using your example I think I can illistarte the point I was trying to make earlier.

          1 + (2*3) by always doing multiplication first we can remove those brackets.

          (1 + 2) * 3 can be rewritten as (1 * 3 )+ (2 * 3) so using the first rule again makes a sense. That is a crappy explaination but I think you get my gist.

          • Kogasa@programming.dev
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            1 year ago

            Your point is not clear.

            1 + (2 * 3) by always doing addition first we can remove those brackets.

            (1 * 3) + (2 * 3) can be rewritten as (1 + 2) * 3 so using the first rule again makes sense.

            Do you see the issue?

            • nLuLukna @sh.itjust.works
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              1 year ago

              I don’t see it mate. So you’re going to have to tell me, sorry.

              The point I’m trying to make is that using Pemdas/Bedmas is the most effiecent way of removing brackets - I actually don’t 100% know that but I doubt it creates hundreds of brackets - if thats slightly clearer.

              • Kogasa@programming.dev
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                1 year ago

                I don’t know how else to explain it. I used your own argument verbatim but with the opposite assumption, that addition takes priority over multiplication. In either case, some expressions can be written without parentheses which require parentheses in the other case.

                • nLuLukna @sh.itjust.works
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                  1 year ago

                  Right well that makes sense. And is also a very good point. I don’t really see why you couldn’t do that. So I guess it is arbitrary. Although you then have the question of which case occurs more commonly, which is imo actually quite interesting, but also entirely pointless, since good luck showing one case to be more than the other. It’s like that door and wheel question.

    • talung@lemmy.talung.org
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      1 year ago

      The one I learnt at the dawn of time was BODMAS.

      bracket of Division Multiplication Addition Subtraction.

      I learnt this in the 70’s early 80’s in South Africa, so not sure if things have changed.

      • Kogasa@programming.dev
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        1 year ago

        B/P are the same (brackets/parentheses) and O/E are the same (order/exponent), and the order of M and D doesn’t matter since those two have equal priority and are evaluated left-to-right. Hence PEMDAS, BODMAS, BEDMAS, etc. are all the same.

  • tetraodon@feddit.it
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    1 year ago

    Ok, I get how applying all the rules of arithmetic wrong you could arrive to 16.

    But how in the holy Pythagoras did someone decide that 2 + 2 * 4 = 13 ?

  • Mothra@mander.xyz
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    1 year ago

    I understand why people get 16. But how do they get 14, 15 and… 13??? Trolling, right?

    • philomory@lemm.ee
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      1 year ago

      I’m not sure if you’re aware or not, but at the moment that photo was taken, he was in the middle of trying to interview then-president Trump.

      I don’t remember what specific thing Trump said to elicit that reaction, and I’m not really in the mood to re-watch the interview to remind myself. Suffice it to say, Trump said a lot of just absolute nonsense.

  • Casmael@geddit.social
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    1 year ago

    If they wanted the multiplication done first they should have put it first if they wanted it done separately they should have put it in brackets. Not my fault some maths guy invented a specific order to do sums in who the fuck cares oh my god we read left to right fucking hell

      • nLuLukna @sh.itjust.works
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        1 year ago

        Yeah but the way you derive the order of operations is way above the average maths student.

        I say that, but its not really that complicated to derive, since you think in terms of the expansion of the naturals to the reals

        My brain is fucking dumb

        • DrRatso@lemmy.world
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          1 year ago

          Im sorry, what? The order of operations is completely arbitrary, it just also happens to be the standart. Not having PEMDAS would simply mean we have to write equations differently. PEMDAS et al only exist to avoid ambiguity as in this image.

          • nLuLukna @sh.itjust.works
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            1 year ago

            Yeah looking at my comment with fresh eyes, I really failed to say anything true.

            But I’m still going to say its not arbitary, since its super fucking convinent and it removes a lot of brackets.

            • DrRatso@lemmy.world
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              1 year ago

              By that reasoning, sure, it is not arbitrary, it might be the most efficient way to resolve things without complicating the notation we have to use. The point about it being arbitrary was more to say that there is no real mathematic basis for it, we have simply agreed to do it this way so everyone applyingnit arrives at the same “correct” solution.

              Arguably it has little value in algebra too, since it tends to be written less ambiguously, tho I have not had to really use algebra much since highschool (weirdly it was not a huge part of medschool, at least here, occasional use in chem and phys only).

        • Zoot@reddthat.com
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          1 year ago

          If pemdas is above the average math student that’s fucked. I learned it in 5th grade.

      • AnarchoYeasty@beehaw.org
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        1 year ago

        Except math isn’t real and was entirely made up. Including the order in which the operations are calculated.

          • AnarchoYeasty@beehaw.org
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            1 year ago

            Math is our representation of real world phenomena. The universe is not calculating any computations when gravity takes effect. This is basic mathematical knowledge that they teach you when you first learn physics. So no, math is not real and is entirely made up.

            • niktemadur@kbin.social
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              1 year ago

              I see what you’re saying. But what if we tweak things a little:
              Math is real, it is numbers that are invented, the discreet packets in a ruler, a measuring stick. Like an imaginary line in a grid, such as the tropics and equator.

    • Tavarin@lemmy.world
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      1 year ago

      Multiplication is just shorthand for multiple additions. so 2x4 is actually 4+4. If you expand out the multiplication the above equation becomes 2+4+4. It’s not arbitrary, it’s just what multiplication represents.