Comment on A fake Facebook event disguised as a math problem has been one of its top posts for 6 months

• SmartmanApps@programming.dev ⁨9⁩ ⁨months⁩ ago

  6 + 4 / 2 is 8 instead of 5?

  The fundamental property of Maths that you have to solve binary operators before unary operators or you end up with wrong answers.

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  • AbidanYre@lemmy.world ⁨9⁩ ⁨months⁩ ago

    But +, -, *, and / are all binary operators?

    As far as I know, the only reason multiplication and division come first is that we’ve all agreed to it. But it can’t be derived in a vacuum as he contends it should be.

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    • SmartmanApps@programming.dev ⁨9⁩ ⁨months⁩ ago

      But +, -, *, and / are all binary operators?

      No, only multiply and divide are. 2+3 is really +2+3, but we don’t write the first plus usually.

      As far as I know, the only reason multiplication and division come first is that we’ve all agreed to it.

      No, they come first because you get wrong answers if you don’t do them first. e.g. 2+3x4=14, not 20. All the rules of Maths exist to make sure you get correct answers. Multiplication is defined as repeated addition - 3x4=3+3+3+3 - hence wrong answers if you do the addition first (just changed the multiplicand, and hence the answer). Ditto for exponents, which are defined as repeated multiplication, a^2=(axa). Order of operations is the process of reducing everything down to adds and subtracts on a number line.

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      • AbidanYre@lemmy.world ⁨9⁩ ⁨months⁩ ago

        Typical examples of binary operations are the addition ( + {\displaystyle +}) and multiplication ( × {\displaystyle \times }) of numbers and matrices

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• barsoap@lemm.ee ⁨10⁩ ⁨months⁩ ago

  Nothing. And that’s why people don’t write equations like that: You either see

       4
  6 + ---
       2
  

  or

   6 + 4
  -------
     2
  

  If you wrote 6 + 4 / 2 in a paper you’d get reviewers complaining that it’s ambiguous, if you want it to be on one line write (6+4) / 2 or 6 + (4/2) or 6 + ⁴⁄₂ or even 0.5 (6 + 2) Working mathematicians never came up with PEMDAS, which disambiguates it without parenthesis, US teachers did. Noone else does it that way because it does not, in the slightest, aid readability.

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  • SmartmanApps@programming.dev ⁨9⁩ ⁨months⁩ ago

    And that’s why people don’t write equations like that

    Says someone who clearly hasn’t looked in any Maths textbooks

    If you wrote 6 + 4 / 2 in a paper you’d get reviewers complaining that it’s ambiguous

    Only if their Maths was very poor. #MathsIsNeverAmbiguous

    Working mathematicians never came up with PEMDAS

    Yes they did.

    which disambiguates it without parenthesis

    It was never ambiguous to begin with.

    Noone else does it that way

    Says someone who has never looked in a non-U.S. Maths textbook - BIDMAS, BODMAS, BEDMAS, all textbooks have one variation or another.

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