• 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 covention 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.

      • 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.

      • 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.”