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YAMP

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  • D Offline
    D Offline
    David Stone
    wrote on last edited by
    #1

    Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


    The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

        a = 9.999999...
      10a = 99.999999...
    

    10a - a = 90
    9a = 90
    a = 10


    I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

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    • D David Stone

      Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


      The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

          a = 9.999999...
        10a = 99.999999...
      

      10a - a = 90
      9a = 90
      a = 10


      I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

      C Offline
      C Offline
      Chris Richardson
      wrote on last edited by
      #2

      Yeah, but 9a != 90. If you use 6 digits after the decimal, 9a == 89.999991. Chris Richardson Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

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      • C Chris Richardson

        Yeah, but 9a != 90. If you use 6 digits after the decimal, 9a == 89.999991. Chris Richardson Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

        D Offline
        D Offline
        David Stone
        wrote on last edited by
        #3

        Assume that the .999999... part goes on ad infinitum.;P


        I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

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        • D David Stone

          Assume that the .999999... part goes on ad infinitum.;P


          I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

          S Offline
          S Offline
          Steven Hicks n 1
          wrote on last edited by
          #4

          David Stone wrote: ad infinitum Isn't that the word you absolutely hate? :p -Steven CP Addict

          By reading this message you are held fully responsible for any of the mispelln's or grammer, issues, found on, codeproject.com.

          For those who were wondering, actual (Linux) Penguins were harmed in creating this message.

          Visit Ltpb.8m.com
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          • D David Stone

            Assume that the .999999... part goes on ad infinitum.;P


            I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

            C Offline
            C Offline
            Chris Richardson
            wrote on last edited by
            #5

            If the .999 goes on forever, all that's different is that the 1 will be way further out. Chris Richardson Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

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            • C Chris Richardson

              If the .999 goes on forever, all that's different is that the 1 will be way further out. Chris Richardson Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

              T Offline
              T Offline
              Tim Smith
              wrote on last edited by
              #6

              Chris is right. 99.999... - 9.999 != 90 Tim Smith I'm going to patent thought. I have yet to see any prior art.

              1 Reply Last reply
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              • D David Stone

                Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


                The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

                    a = 9.999999...
                  10a = 99.999999...
                

                10a - a = 90
                9a = 90
                a = 10


                I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                B Offline
                B Offline
                Brit
                wrote on last edited by
                #7

                This may not be right, but...

                     a = 9.9999...  = 10  - 1/infinity
                   10a = 99.9999... = 100 - 10/infinity
                

                10a - a = 90? no
                10a - a = (100 - 10/infinity) - (10 - 1/infinity)
                = ( 90 - 9/infinity) = 89.9999999...

                ------------------------------------------ "Isn't it funny how people say they'll never grow up to be their parents, then one day they look in the mirror and they're moving aircraft carriers into the Gulf region?" - The Onion

                1 Reply Last reply
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                • D David Stone

                  Assume that the .999999... part goes on ad infinitum.;P


                  I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                  T Offline
                  T Offline
                  Taka Muraoka
                  wrote on last edited by
                  #8

                  Isn't the second line wrong? 10a = 99.999999...0 :-)


                  he he he. I like it in the kitchen! - Marc Clifton (on taking the heat when being flamed) Awasu v0.4a[^]: A free RSS reader with support for Code Project.

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                  • T Taka Muraoka

                    Isn't the second line wrong? 10a = 99.999999...0 :-)


                    he he he. I like it in the kitchen! - Marc Clifton (on taking the heat when being flamed) Awasu v0.4a[^]: A free RSS reader with support for Code Project.

                    C Offline
                    C Offline
                    Chris Richardson
                    wrote on last edited by
                    #9

                    I don't think so. Multiplying it by 10 just shifts the decimal place right by one place. Chris Richardson Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

                    T 1 Reply Last reply
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                    • C Chris Richardson

                      If the .999 goes on forever, all that's different is that the 1 will be way further out. Chris Richardson Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

                      D Offline
                      D Offline
                      David Stone
                      wrote on last edited by
                      #10

                      No it won't. The repeating nines will cancel each other out. If you have 3.99... - 3.99... doesn't that equal 0?


                      I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                      N 1 Reply Last reply
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                      • D David Stone

                        Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


                        The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

                            a = 9.999999...
                          10a = 99.999999...
                        

                        10a - a = 90
                        9a = 90
                        a = 10


                        I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                        N Offline
                        N Offline
                        Nitron
                        wrote on last edited by
                        #11

                        Nothing! 10 is an asymptote. It's like having:

                          \_        \_
                          |     1  |
                        

                        lim |y = --- | ====> y = 0
                        | x | x-->(infinity)
                        ¯ ¯

                        - Nitron


                        "Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

                        N 1 Reply Last reply
                        0
                        • C Chris Richardson

                          I don't think so. Multiplying it by 10 just shifts the decimal place right by one place. Chris Richardson Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

                          T Offline
                          T Offline
                          Taka Muraoka
                          wrote on last edited by
                          #12

                          Not true (I think :~) Multiplying by ten doesn't mean you play games with the symbols you use to write the number with, it means you add it ten times. Multiplying by 10 has the side-effect of "moving the decimal place" but: 1.234 * 10 = 12.340 if you want to keep the same number of decimal places. But this doesn't work if you have an infinite number of decimal places i.e. 9.999... * 10 != 99.999... Brit posted something where he used 1/infinity but you can't do that. Infinity is a concept, not a number.


                          he he he. I like it in the kitchen! - Marc Clifton (on taking the heat when being flamed) Awasu v0.4a[^]: A free RSS reader with support for Code Project.

                          B 1 Reply Last reply
                          0
                          • D David Stone

                            No it won't. The repeating nines will cancel each other out. If you have 3.99... - 3.99... doesn't that equal 0?


                            I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                            N Offline
                            N Offline
                            Nick Seng
                            wrote on last edited by
                            #13

                            not true, we have to assume that a and 10a have the same number of significant digits.What this means is that:

                            a = 9.999 ... 999
                            then
                            10a = 99.99 ... 990
                            thus
                            10a - a = 89.99 ... 991

                            Notorious SMC


                            The difference between the almost-right word & the right word is a really large matter - it's the difference between the lightning bug and the Lightning Mark Twain
                            Get your facts first, and then you can distort them as much as you please Mark Twain

                            1 Reply Last reply
                            0
                            • N Nitron

                              Nothing! 10 is an asymptote. It's like having:

                                \_        \_
                                |     1  |
                              

                              lim |y = --- | ====> y = 0
                              | x | x-->(infinity)
                              ¯ ¯

                              - Nitron


                              "Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

                              N Offline
                              N Offline
                              Nick Seng
                              wrote on last edited by
                              #14

                              X| X| X| X| Arrghh! I thought i left all those calculus back in College!! :Runs around in fear, remembering the nightmare of calculus: Notorious SMC


                              The difference between the almost-right word & the right word is a really large matter - it's the difference between the lightning bug and the Lightning Mark Twain
                              Get your facts first, and then you can distort them as much as you please Mark Twain

                              1 Reply Last reply
                              0
                              • D David Stone

                                Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


                                The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

                                    a = 9.999999...
                                  10a = 99.999999...
                                

                                10a - a = 90
                                9a = 90
                                a = 10


                                I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                                M Offline
                                M Offline
                                Michael Dunn
                                wrote on last edited by
                                #15

                                I like this version: 0.9 / 9 = 0.1 1 / 9 = 0.1 Thus 0.9 = 1 :cool: --Mike-- When 900 years old you reach, look as good you will not. Hmm. 1ClickPicGrabber - Grab & organize pictures from your favorite web pages, with 1 click! My really out-of-date homepage Sonork-100.19012 Acid_Helm

                                1 Reply Last reply
                                0
                                • D David Stone

                                  Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


                                  The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

                                      a = 9.999999...
                                    10a = 99.999999...
                                  

                                  10a - a = 90
                                  9a = 90
                                  a = 10


                                  I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                                  P Offline
                                  P Offline
                                  peterchen
                                  wrote on last edited by
                                  #16

                                  If it goes on ad infinitum, 9.9... = 10. because 0.9... = 3* 1/3 = 1


                                  Those who not hear the music think the dancers are mad.  [sighist] [Agile]

                                  1 Reply Last reply
                                  0
                                  • D David Stone

                                    Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


                                    The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

                                        a = 9.999999...
                                      10a = 99.999999...
                                    

                                    10a - a = 90
                                    9a = 90
                                    a = 10


                                    I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                                    G Offline
                                    G Offline
                                    geoneoration
                                    wrote on last edited by
                                    #17

                                    if your assumption is > a = 9.999999... > 10a = 99.999999... > 10a - a = 90 > 9a = 90 > a = 10 change a to 1.1111111... or 2.22222222... or 3.33333333... or ......... the result are the same that ten will equal 1.111111... or 2.222222... or 3.333333... or ...... :)

                                    Richard DeemingR 1 Reply Last reply
                                    0
                                    • D David Stone

                                      Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


                                      The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

                                          a = 9.999999...
                                        10a = 99.999999...
                                      

                                      10a - a = 90
                                      9a = 90
                                      a = 10


                                      I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                                      K Offline
                                      K Offline
                                      KaRl
                                      wrote on last edited by
                                      #18

                                      The infinite is not equal to (infinite - 1) ?


                                      Angels banished from heaven have no choice but to become demons Cowboy Bebop

                                      1 Reply Last reply
                                      0
                                      • D David Stone

                                        Yet Another Math Puzzle Proof that playing math games with smart people isn't fun. If I gave that to my friends, they wouldn't be able to spot it for at least a little bit. Anyway, here's another one:


                                        The following is what seems to be a mathematical proof that ten equals 9.999999.... What's wrong with it?

                                            a = 9.999999...
                                          10a = 99.999999...
                                        

                                        10a - a = 90
                                        9a = 90
                                        a = 10


                                        I don't know whether it's just the light but I swear the database server gives me dirty looks everytime I wander past. -Chris Maunder Microsoft has reinvented the wheel, this time they made it round. -Peterchen on VS.NET

                                        K Offline
                                        K Offline
                                        Kastellanos Nikos
                                        wrote on last edited by
                                        #19

                                        It's the second line. You must see it as: a = 9.999999... 10a = 10(9.999999...) 10a - a = 9(9.999999...) - - - - - - - - - - - - - - - - - - Memory leaks is the price we pay \0 01234567890123456789012345678901234

                                        1 Reply Last reply
                                        0
                                        • G geoneoration

                                          if your assumption is > a = 9.999999... > 10a = 99.999999... > 10a - a = 90 > 9a = 90 > a = 10 change a to 1.1111111... or 2.22222222... or 3.33333333... or ......... the result are the same that ten will equal 1.111111... or 2.222222... or 3.333333... or ...... :)

                                          Richard DeemingR Offline
                                          Richard DeemingR Offline
                                          Richard Deeming
                                          wrote on last edited by
                                          #20

                                          No:

                                          a = 1.111...
                                          10a = 11.111...
                                          10a - a = 10
                                          9a = 10
                                          a = 10 / 9 = 1 + 1/9

                                          a = 2.222...
                                          10a = 22.222...
                                          10a - a = 20
                                          9a = 20
                                          a = 20 / 9 = 2 + 2/9

                                          etc.


                                          "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

                                          "These people looked deep within my soul and assigned me a number based on the order in which I joined" - Homer

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