• @cerement@slrpnk.net
    52•1 year ago
    • 16 is the right answer if you use PEMDAS only: (8 ÷ 2) × (2 + 2)
    • 1 is the right answer if you use implicit/explicit with PEMDAS: 8 ÷ (2 × (2 + 2))
    • both are correct answers (as in if you don’t put in extra parentheses to reduce ambiguity, you should expect expect either answer)
    • this is also one of the reasons why postfix and prefix notations have an advantage over infix notation
      • postfix (HP, RPN, Forth): 2 2 + 8 2 ÷ × .
      • prefix (Lisp): (× (÷ 8 2) (+ 2 2))
      • synae[he/him]English
        2•1 year ago

        PEMDAS is actually (PE)(MD)(AS). Those that are grouped together have equal precedence and are evaluated left to right.

        8 / 2 * (2+2)

        8 / 2 * 4

        4 * 4

        16

        Edit to fix formatting, maybe?

    • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱English
      2•1 year ago

      16 is the right answer if you use PEMDAS only: (8 ÷ 2) × (2 + 2)

      You added brackets and changed the answer. 2(2+2) is a single term, and if you break it up then you change the answer (because now the (2+2) is in the numerator instead of in the denominator).

      1 is the right answer

      The only right answer

      both are correct answers

      Nope, 1 is the only correct answer.

      this is also one of the reasons why postfix and prefix notations have an advantage over infix notation

      Except they don’t. This isn’t a notation problem, it’s a people don’t remember the rules of Maths problem.

    • @brian@programming.dev
      3•1 year ago

      prefix notation doesn’t need parentheses either though, at least in this case. lisp uses them for readability and to get multiple arity operators. infix doesn’t have any ambiguity either if you parenthesize all operations like that.