• 4am@lemm.ee
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    11 months ago

    PEMDAS

    Parenthesis, exponents, multiplication, division, addition, subtraction.

    The rule is much older than me and they taught it in school. Nothing ambiguous about it, homie. The phone app is fucked up. Calculator nailed it.

    • Coreidan@lemmy.world
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      11 months ago

      Left to right. If you’re following ALL of the rules of PEMDAS then the answer is 16

        • Zagorath@aussie.zone
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          11 months ago

          The answer is 1, but the logic you’ve used to get there is a little off. Different groups actually follow different logic, but they usually arrive at the same end-point.

          The American Mathematical Society goes:

          • Brackets
          • Indices
          • Multiplication indicated by juxtaposition
          • Regular multiplication and division
          • Addition and subtraction

          While the American Physical Society does

          • Brackets
          • Indices
          • Multiplication
          • Division
          • Addition and subtraction

          In both cases, addition and subtraction are equal in priority (this solves the problem brought up by a different comment where following primary school BIDMAS would mean 8-4+2=2). In one case (and this is the way I prefer to do it) they solve the problem by declaring that implicit multiplication is done before division, but explicit multiplication with the × sign follows the same rules you would have learnt in primary school. The other says all multiplication is done before division, including explicit multiplication.

        • NikkiNikkiNikki@kbin.social
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          11 months ago

          Multiplication and division have the same priority, whichever one comes first LTR is the one that gets resolved first, so it’s (8 / 2) * 4

        • Justin@lemmy.jlh.name
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          11 months ago

          By that logic: 8-2+4=2

          Of course, it could be kind of ambiguous, but typical convention gives multiplication/division the same priority, as it does addition/subtraction.

          And in general, you need to go left to right when dealing with division and subtraction, if other operations have the same priority.

    • hallettj@beehaw.org
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      11 months ago

      The comment from subignition explains that the phone’s answer, 16, is what you get by strictly following PEMDAS: the rule is that multiplication and division have the same precedence, and you evaluate them from left-to-right.

      The calculator uses a different convention where either multiplication has higher priority than division, or where “implicit” multiplication has higher priority (where there is no multiply sign between adjacent expressions).

        • hallettj@beehaw.org
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          11 months ago

          The parentheses step only covers expressions inside parentheses. That’s 2 + 2 in this case. The times-2 part is outside the parentheses so it’s evaluated in a different step.

    • arisunz@lemmy.blahaj.zone
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      11 months ago

      i know about pemdas and also my brother in christ half the people in the comments are saying the phone app is right lmao

      edit: my first answer was 16