Comment on SBA #119 maths

• LORDSMEGMA@sh.itjust.works ⁨3⁩ ⁨weeks⁩ ago

  No. After you do the parentheses, multiplication and division are done left to right.

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  • StarvingMartist@sh.itjust.works ⁨3⁩ ⁨weeks⁩ ago

    Yeah, gonna need to see a proof before I trust ANYONE on lemmy

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    • dalekcaan@feddit.nl ⁨3⁩ ⁨weeks⁩ ago

      en.wikipedia.org/wiki/Order_of_operations

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    • LostCarcosan@lemmy.today ⁨3⁩ ⁨weeks⁩ ago

      Multiplication/division and addition/subtraction both happen left to right. They… Didn’t teach you that in school?

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    • LORDSMEGMA@sh.itjust.works ⁨3⁩ ⁨weeks⁩ ago

      Multiplication and division are the same operation

      6 * (1 / 2) = 6 / 2

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• ChairmanMeow@programming.dev ⁨3⁩ ⁨weeks⁩ ago

  It can be both depending on how you handle operator precendence.

  PEMDAS definitely doesn’t result in 1, but in 9, since under PEMDAS multiplication and division have the same priority (and thus should resolve left-to-right). So, you should resolve to 9 (6/2(2+1) => 6/2(3) => 6/23 => 33 => 9).

  However, there’s also PEJMDAS, which suggests that implied multiplication has an operator precedence greater than regular multiplication/division (J for Juxtaposition). This version says you should do 6/2(2+1) => 6/(22 + 21) => 6/(4+2) => 6/6 => 1.

  The issue is that there is no universal agreement on which is correct. Most textbooks don’t even use the / operator, but instead rely on writing out the full fraction like ⁶⁄₂₍₂₊₁₎ or ⁶⁄₂(2+1). This removes any ambiguity there might be, and thus they don’t touch on which one is actually correct.

  Most (but not all) calculators these days will treat implied multiplication the same as regular multiplication, so you get 9 in the given example. Most programming languages do the same, or outright disallow implied multiplication because it only confuses people. Academics won’t ever use the ambiguous notation and will make sure to remove any ambiguity by either adding parentheses or using a notation like ⁶⁄₂₍₂₊₁₎, which makes things much more clear.

  Neither 9 nor 1 is wrong, the question is just stupid.

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  • db2@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

    Now do 2+2=5

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• remon@ani.social ⁨3⁩ ⁨weeks⁩ ago

  No you don’t, decision is on the left, so it comes first

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• probablymissing@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

  there’s no way you’re serious Image

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  • agent_nycto@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

    :y

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    • EmpathicVagrant@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

      P/E/M(&)D/A(&)S

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• Atomic@sh.itjust.works ⁨3⁩ ⁨weeks⁩ ago

  [deleted]

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  • remon@ani.social ⁨3⁩ ⁨weeks⁩ ago

    The precedence goes like this:

    parentheses > exponents > (multiplication = division) > (addition = substraction)

    If you encounter operators with the same precedence (like multiplication and division) you go by the order they appear in the equation, left to right.

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    • Atomic@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

      Yes. I am well aware. 6 ÷ 2 * (2+1) = (2+1) * 6 ÷ 2 = (6 * (2+1))÷2 = 6 * (2+1) ÷ 2

      What he wanted to do is 6 ÷ (2 * (2+1))

      But this just comes down to if you treat 2(2+1) as one or two expressions.

      And honestly, i don’t blame anyone for thinking one way or the other. Because i think most people understand that we wanted to write (2(2+1)), just that the overall parentheses is implied

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