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Math Puzzle

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  • J Joaquin M Lopez Munoz

    0 is simple, so is 1. For the rest: n=-log2[log2(sqrt(sqrt(...n times...(2)...))))] Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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    Shree
    wrote on last edited by
    #21

    That's it!!

    W 1 Reply Last reply
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    • J Jorgen Sigvardsson

      You have a degree in mathematics, don't you? :) -- I am on fire. Do you need a light?

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      Joaquin M Lopez Munoz
      wrote on last edited by
      #22

      No I don't :) I'm a electrical engineer, but used to be fond of these kind of quizzes when I was younger. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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      • J Joaquin M Lopez Munoz

        No I don't :) I'm a electrical engineer, but used to be fond of these kind of quizzes when I was younger. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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        Jorgen Sigvardsson
        wrote on last edited by
        #23

        Have you read Gödel Escher Bach - The Eternal Golden Braid? Your solution reminded me a lot of the authors (Hofstadter) representation of the natural numbers. He defined it by an axiom 0 (zero) and an operation S (successor). Your log/sqrt solution for simulating S gave me a flashback.. :) -- I am on fire. Do you need a light?

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        • S Shree

          How can you write any positive integer using only three 2s and any mathematical operations?

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          Wesner Moise
          wrote on last edited by
          #24

          The answer would involve some constructed function f(x) that increases x by 1. Then, applying f(x) to itself would allow all the positive numbers be generated. IE, f(2) = 3, and f(f(2)) = 4, and f^n(2) = 2+n-1. Since 2 is the only number we are allow, f(2) is really the only possibility, unless you want to consider f(22) or f(222) or f(2/2) or etc, but then we wastes our valuable 2s. Some functions f(x) that satisfy, are: f(x) = -(~x) --> bitwise negation followed by arithmetic negation f(x) = combination of logs and sqrts of a prior post so, my solution, the first f(x), can obtain, for example, 5 which is -~-~-~2. Thanks, Wes

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          • S Shree

            That's it!!

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            Wesner Moise
            wrote on last edited by
            #25

            my answer -~-~...-~2 is simpler and requires only one 2.

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            • W Wesner Moise

              The answer would involve some constructed function f(x) that increases x by 1. Then, applying f(x) to itself would allow all the positive numbers be generated. IE, f(2) = 3, and f(f(2)) = 4, and f^n(2) = 2+n-1. Since 2 is the only number we are allow, f(2) is really the only possibility, unless you want to consider f(22) or f(222) or f(2/2) or etc, but then we wastes our valuable 2s. Some functions f(x) that satisfy, are: f(x) = -(~x) --> bitwise negation followed by arithmetic negation f(x) = combination of logs and sqrts of a prior post so, my solution, the first f(x), can obtain, for example, 5 which is -~-~-~2. Thanks, Wes

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              Ryan Binns
              wrote on last edited by
              #26

              Brilliant! Well done :)

              Ryan

              "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

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              • W Wesner Moise

                The answer would involve some constructed function f(x) that increases x by 1. Then, applying f(x) to itself would allow all the positive numbers be generated. IE, f(2) = 3, and f(f(2)) = 4, and f^n(2) = 2+n-1. Since 2 is the only number we are allow, f(2) is really the only possibility, unless you want to consider f(22) or f(222) or f(2/2) or etc, but then we wastes our valuable 2s. Some functions f(x) that satisfy, are: f(x) = -(~x) --> bitwise negation followed by arithmetic negation f(x) = combination of logs and sqrts of a prior post so, my solution, the first f(x), can obtain, for example, 5 which is -~-~-~2. Thanks, Wes

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                Shree
                wrote on last edited by
                #27

                Great!!

                1 Reply Last reply
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                • W Wesner Moise

                  The answer would involve some constructed function f(x) that increases x by 1. Then, applying f(x) to itself would allow all the positive numbers be generated. IE, f(2) = 3, and f(f(2)) = 4, and f^n(2) = 2+n-1. Since 2 is the only number we are allow, f(2) is really the only possibility, unless you want to consider f(22) or f(222) or f(2/2) or etc, but then we wastes our valuable 2s. Some functions f(x) that satisfy, are: f(x) = -(~x) --> bitwise negation followed by arithmetic negation f(x) = combination of logs and sqrts of a prior post so, my solution, the first f(x), can obtain, for example, 5 which is -~-~-~2. Thanks, Wes

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                  Wesner Moise
                  wrote on last edited by
                  #28

                  Regarding, my answer, -~-~-~ ... -~2, it is can be done with log n operations by appropriate using replacing some of the inner operations with the sqr or factorial functions. Thanks, Wes

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                  • J Jorgen Sigvardsson

                    Have you read Gödel Escher Bach - The Eternal Golden Braid? Your solution reminded me a lot of the authors (Hofstadter) representation of the natural numbers. He defined it by an axiom 0 (zero) and an operation S (successor). Your log/sqrt solution for simulating S gave me a flashback.. :) -- I am on fire. Do you need a light?

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                    Joaquin M Lopez Munoz
                    wrote on last edited by
                    #29

                    Yes, that was a nice book. If you like this sort of stuff, a lighter, but equally fun book on logic matters is What is the Name of this Book? by Raymond Smullyan. It has some Gödelian discussions in the last chapters. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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                    • R Ryan Binns

                      Atlantys wrote: The largest number I can do is: 4194304 (2^22) Really?! What about 222! = approx 1.12*10426

                      Ryan

                      "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

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                      Atlantys
                      wrote on last edited by
                      #30

                      Doh! I was trying to use an operator that causes the system to grow large very quickly. Hence ^. I complete forget about !. Dammit! I suppose that's what staying up late does to the brain. Of course... you can then do ((222!)!), etc. :~ :~ I prefer to wear gloves when using it, but that's merely a matter of personal hygiene [Roger Wright on VB] Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning. [Rich Cook]

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