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

• HereIAm@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

  Except it does matter. I left some examples for another post with multiplication and division, I’ll give you some addition and subtraction to see order matter with those operations as well.

  Let’s take:
  1 + 2 - 3 + 4

  Addition first:
  (1 + 2) - (3 + 4)
  3 - 7 = -4

  Subtraction first:
  1 + (2 - 3) + 4
  1 + (-1) + 4 = 4

  Right to left:
  1 + (2 - (3 + 4))
  1 + (2 - 7)
  1 + (-5) = -4

  Left to right:
  ((1 + 2) - 3) + 4 (3 - 3) + 4 = 4

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  • SmartmanApps@programming.dev ⁨1⁩ ⁨day⁩ ago

    Except it does matter

    No it doesn’t. You disobeying the rules and getting lots of wrong answers in your examples doesn’t change that.

    I left some examples for another post with multiplication and division

    Which you did wrong.

    I’ll give you some addition and subtraction to see order matter with those operations as well

    And I’ll show you it doesn’t matter when you do it correctly

    Subtraction first: 1 + (2 - 3) + 4 1 + (-1) + 4 = 4

    Nope. Right answer for wrong reason - you only co-incidentally got the answer right. -3+1+2+4=-3+7=4

    Right to left: 1 + (2 - (3 + 4)) 1 + (2 - 7) 1 + (-5) = -4

    Nope. 4-3+2+1=1+2+1=3+1=4

    Edit: You can argue that, for example, the addition first could be (1 + 2) + (-3 + 4)

    Or you could just do it correctly in the first place, always obeying Left Associativity and never adding Brackets

    in my opinion that’s another ambiguous case

    There aren’t ANY ambiguous cases. In every case it’s equal to 4. If you didn’t get 4, then you made a mistake and got a wrong answer.

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  • troistigrestristes@lemmy.eco.br ⁨3⁩ ⁨weeks⁩ ago

    Oh, but of course the statement changes if you add parentheses. Basically, you’re changing the effective numbers that are being used, because the parentheses act as containers with a given value (you even showed the effective numbers in your examples).

    Get this : + 1 - 1 + 1 - 1 + 1 - 1 + 1

    You can change the result several times by choosing where you want to put the parentheses. However, the order of operations of same priority inside a container (parentheses) does not change the resulting value of the container.

    In the example, there were no parentheses, so no ambiguity (there wouldn’t be any ambiguity with parentheses either, the correct way of calculating would just change), and I don’t think you can add “ambiguity” by adding parentheses — you’re just changing the effective expression to be evaluated.

    By the way, this is the reason why I absolutely overuse parentheses in my engineering code. It can be redundant, but at least I am SURE that it is going to follow the order that I wanted.

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    • SmartmanApps@programming.dev ⁨1⁩ ⁨day⁩ ago

      Oh, but of course the statement changes if you add parentheses

      It sure does, but they don’t seem to understand that.

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