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Math(s) problem - puzzle

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  • Greg UtasG Greg Utas

    Yeah, you're both on the AR page. :-D

    Robust Services Core | Software Techniques for Lemmings | Articles
    The fox knows many things, but the hedgehog knows one big thing.

    D Offline
    D Offline
    dandy72
    wrote on last edited by
    #25

    :-D

    1 Reply Last reply
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    • D dbrenth

      My teacher asked me to write a program on the board and solve it. I wrote:

      230 - 220 x 0.5

      and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.

      Brent

      OriginalGriffO Offline
      OriginalGriffO Offline
      OriginalGriff
      wrote on last edited by
      #26

      And today you learn that nobody likes a smartarse ... :laugh:

      "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

      "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
      "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

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      0
      • OriginalGriffO OriginalGriff

        And today you learn that nobody likes a smartarse ... :laugh:

        "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

        D Offline
        D Offline
        DRHuff
        wrote on last edited by
        #27

        OriginalGriff wrote:

        nobody likes a smartarse

        Maybe he should brace himself for the reactions to come?

        If you can't laugh at yourself - ask me and I will do it for you.

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        • D dandy72

          I thought about that...but who provides answers as a factorial?

          C Offline
          C Offline
          CPallini
          wrote on last edited by
          #28

          Bernoulli?

          "In testa che avete, Signor di Ceprano?" -- Rigoletto

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          • D dbrenth

            My teacher asked me to write a program on the board and solve it. I wrote:

            230 - 220 x 0.5

            and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.

            Brent

            C Offline
            C Offline
            Chris Maunder
            wrote on last edited by
            #29

            Very clever :thumbsup:

            cheers Chris Maunder

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            • C CPallini

              42. :-D

              "In testa che avete, Signor di Ceprano?" -- Rigoletto

              L Offline
              L Offline
              Lost User
              wrote on last edited by
              #30

              42! Looks as windoze coders are lacking kindergartner knowledge of math ... no wonder "fake news " are taking over the world

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              • K Keith Barrow

                3! - 1 I think you'll find :) It's curious - nearly everyone I know was taught BODMAS - its the same as PEDMAS, but B=Brackets, O="of". PEDMAS is probably better. Also the great Indian chief "SOH-CAH-TOA". I wonder if they still teach the latter in schools.

                KeithBarrow.net[^] - It might not be very good, but at least it is free!

                D Offline
                D Offline
                Dougy83
                wrote on last edited by
                #31

                I hadn't heard of PEDMAS before; I'm guessing it's some kind of Hollywood holiday.

                R 1 Reply Last reply
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                • D dbrenth

                  My teacher asked me to write a program on the board and solve it. I wrote:

                  230 - 220 x 0.5

                  and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.

                  Brent

                  B Offline
                  B Offline
                  Bob Beechey
                  wrote on last edited by
                  #32

                  The teacher was not embarrassed but shocked that any student could be so wrong. The division MUST be carried out before the subtraction. 230 – 220 × 0.5 = 230 – 110 = 120. Try it in any scientific calculator or programming language. You are alone (I hope) in thinking the answer is 5. Are you perhaps joking?

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                  • D Daniel Pfeffer

                    You are wrong, the teacher is right. The order of precedence in mathematical operations is (mnemonic PEMDAS): Parentheses Exponentiation Multiplication & Division Addition & Subtraction If two operations have the same precedence, they are evaluated from left to right. Your problem may be rewritten as 230 - (220 x 0.5), the answer to which is obviously not 5.

                    Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

                    A Offline
                    A Offline
                    AnthonyLondon
                    wrote on last edited by
                    #33

                    You write "the answer to which is obviously not 5". Nobody ever said that. The OP sais that he "announced that the answer was 5!". Do you see the difference? The exclamation mark. The answer is 5! (five factorial) and 5!=5*4*3*2*1=120 so 5! is the correct answer :-)

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                    • Greg UtasG Greg Utas

                      Yeah, you're both on the AR page. :-D

                      Robust Services Core | Software Techniques for Lemmings | Articles
                      The fox knows many things, but the hedgehog knows one big thing.

                      D Offline
                      D Offline
                      Daniel Pfeffer
                      wrote on last edited by
                      #34

                      Hey, I resemble that! :mad: :)

                      Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

                      1 Reply Last reply
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                      • D Daniel Pfeffer

                        You are wrong, the teacher is right. The order of precedence in mathematical operations is (mnemonic PEMDAS): Parentheses Exponentiation Multiplication & Division Addition & Subtraction If two operations have the same precedence, they are evaluated from left to right. Your problem may be rewritten as 230 - (220 x 0.5), the answer to which is obviously not 5.

                        Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

                        M Offline
                        M Offline
                        Member 14174460
                        wrote on last edited by
                        #35

                        In the UK they teach BODMAS as the order of precedence Brackets Operations Division MMultiplication AAddition SSubtraction see Order of operations - Year 6 - P7 - Maths - Home Learning with BBC Bitesize - BBC Bitesize[^]

                        OriginalGriffO 1 Reply Last reply
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                        • D Daniel Pfeffer

                          You are wrong, the teacher is right. The order of precedence in mathematical operations is (mnemonic PEMDAS): Parentheses Exponentiation Multiplication & Division Addition & Subtraction If two operations have the same precedence, they are evaluated from left to right. Your problem may be rewritten as 230 - (220 x 0.5), the answer to which is obviously not 5.

                          Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

                          M Offline
                          M Offline
                          Member 14174460
                          wrote on last edited by
                          #36

                          In the UK they teach BODMAS as the order of precedence Brackets Operations Division MMultiplication AAddition SSubtraction see Order of operations - Year 6 - P7 - Maths - Home Learning with BBC Bitesize - BBC Bitesize[^]

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                          0
                          • M Member 14174460

                            In the UK they teach BODMAS as the order of precedence Brackets Operations Division MMultiplication AAddition SSubtraction see Order of operations - Year 6 - P7 - Maths - Home Learning with BBC Bitesize - BBC Bitesize[^]

                            OriginalGriffO Offline
                            OriginalGriffO Offline
                            OriginalGriff
                            wrote on last edited by
                            #37

                            Please don't repost if your comment does not appear immediately: both of these went to moderation and required a human being to review them for publication. In order to prevent you being kicked off as a spammer, both had to be accepted, and then I have to clean up the spares. Have a little patience, please! I've deleted the other version.

                            "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

                            "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
                            "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt

                            1 Reply Last reply
                            0
                            • D dbrenth

                              My teacher asked me to write a program on the board and solve it. I wrote:

                              230 - 220 x 0.5

                              and announced that the answer was 5! My teacher claimed I was incorrect, but I was not. Can you please explain it to him? Thanks Hint: My teacher was quite embarrassed when I actually said the answer out loud.

                              Brent

                              M Offline
                              M Offline
                              maze3
                              wrote on last edited by
                              #38

                              this is excellent! :doh:

                              1 Reply Last reply
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                              • D dandy72

                                I thought about that...but who provides answers as a factorial?

                                R Offline
                                R Offline
                                rob tillaart
                                wrote on last edited by
                                #39

                                A statisticus / mathematician will provide answers as factorial as often numbers are too big to write down. E.g. 5! is quite easy but 7000000000! is huge. Assuming the world population is 7000000000, 7000000000! is approximately the number of ways you can put their names in a list. As there are people with the same name the number is actually less but still huge. There are even statistic problems where numbers like n!! (n factorial factorial *) are used which can be even "bigger than huge". *) besides "n factorial factorial", there exist "n double factorial" which is n x (n-2) x (n-4) ... x 1)

                                D 1 Reply Last reply
                                0
                                • K Keith Barrow

                                  3! - 1 I think you'll find :) It's curious - nearly everyone I know was taught BODMAS - its the same as PEDMAS, but B=Brackets, O="of". PEDMAS is probably better. Also the great Indian chief "SOH-CAH-TOA". I wonder if they still teach the latter in schools.

                                  KeithBarrow.net[^] - It might not be very good, but at least it is free!

                                  P Offline
                                  P Offline
                                  Prune etna
                                  wrote on last edited by
                                  #40

                                  Rather than the Indian chief, we were taught the great Welsh anthem: Sons of Harlech Come and Harken To our Anthem A geographic thing, I suppose. We were 50 miles from Wales but several thousand from the Indians.

                                  1 Reply Last reply
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                                  • D Daniel Pfeffer

                                    You are wrong, the teacher is right. The order of precedence in mathematical operations is (mnemonic PEMDAS): Parentheses Exponentiation Multiplication & Division Addition & Subtraction If two operations have the same precedence, they are evaluated from left to right. Your problem may be rewritten as 230 - (220 x 0.5), the answer to which is obviously not 5.

                                    Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

                                    P Offline
                                    P Offline
                                    Peter Kelley 2021
                                    wrote on last edited by
                                    #41

                                    Note that he said "5!", not "5".
                                    He might have given it away too big a clue if he had ended his sentence properly with a period like "...I said the answer is 5!."
                                    Good nerdy riddle.

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                                    • R Rick York

                                      If you solve it left-to-right, ignoring precedence order, then the answer is 5. An old TI calculator would give you that answer. Today's windows calculator will not: it says 120 because the multiplication is done first.

                                      "They have a consciousness, they have a life, they have a soul! Damn you! Let the rabbits wear glasses! Save our brothers! Can I get an amen?"

                                      P Offline
                                      P Offline
                                      Peter Kelley 2021
                                      wrote on last edited by
                                      #42

                                      "5!" = 120
                                      It's a clever nerdy riddle. I like it!
                                      I wonder if I'd have been hassled after math class for giving such an answer? and I just noticed that Microsoft Excel doesn't recognize factorials.

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                                      • OriginalGriffO OriginalGriff

                                        And today you learn that nobody likes a smartarse ... :laugh:

                                        "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

                                        D Offline
                                        D Offline
                                        dbrenth
                                        wrote on last edited by
                                        #43

                                        Quote:

                                        smartarse

                                        I'm owning that.

                                        Brent

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                                        0
                                        • B Bob Beechey

                                          The teacher was not embarrassed but shocked that any student could be so wrong. The division MUST be carried out before the subtraction. 230 – 220 × 0.5 = 230 – 110 = 120. Try it in any scientific calculator or programming language. You are alone (I hope) in thinking the answer is 5. Are you perhaps joking?

                                          D Offline
                                          D Offline
                                          dbrenth
                                          wrote on last edited by
                                          #44

                                          As with a few readers, you missed the ! after the 5.

                                          Brent

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