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Hardcore Maths Question

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  • R Raj Lal

    Ok lets me be the first to ask a maths question Find a number which 1. divided by 10 gives a remainder 9 2. divided by 9 gives remainder 8 --- --- so on till divided by 2 gives a remainder 1 Any one ?

    Omit Needless Words - Strunk, William, Jr.


    Online Project Management
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    Jon Sagara
    wrote on last edited by
    #16

    N(1) = 2519 N(2) = 2519 + 2520 = 5039 N(3) = 2519 + 2520 + 2520 = 7559 N(4) = 2519 + 2520 + 2520 + 2520 = 10079 ... N(n) = 2519 + (n - 1)*(2520) No idea what the heck it means, though. Care to enlighten us mathematically-challenged folks?

    Jon Sagara When I grow up, I'm changing my name to Joe Kickass! My Site | My Blog | My Articles

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    • J Jon Sagara

      N(1) = 2519 N(2) = 2519 + 2520 = 5039 N(3) = 2519 + 2520 + 2520 = 7559 N(4) = 2519 + 2520 + 2520 + 2520 = 10079 ... N(n) = 2519 + (n - 1)*(2520) No idea what the heck it means, though. Care to enlighten us mathematically-challenged folks?

      Jon Sagara When I grow up, I'm changing my name to Joe Kickass! My Site | My Blog | My Articles

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      leppie
      wrote on last edited by
      #17

      Jon Sagara wrote:

      N(n) = 2519 + (n - 1)*(2520)

      N(n) = (n * 2520) - 1 = 2520n - 1

      **

      xacc.ide-0.2.0.50 - now with partial MSBuild support!

      **

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      • J Jon Sagara

        N(1) = 2519 N(2) = 2519 + 2520 = 5039 N(3) = 2519 + 2520 + 2520 = 7559 N(4) = 2519 + 2520 + 2520 + 2520 = 10079 ... N(n) = 2519 + (n - 1)*(2520) No idea what the heck it means, though. Care to enlighten us mathematically-challenged folks?

        Jon Sagara When I grow up, I'm changing my name to Joe Kickass! My Site | My Blog | My Articles

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        leppie
        wrote on last edited by
        #18

        Some other interesting and useless observations:

        1*2*3*4*5*6*7*8*9 is divisible by 2520 = 144
        2520 is divisible by 2 * 3 * 5 * 7 = 12 (product of prime 1 - 9)
        4 * 6 * 8 * 9 is divisible by 144 = 12 (product of 'non' prime 1 - 9)

        :doh:

        **

        xacc.ide-0.2.0.50 - now with partial MSBuild support!

        **

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        • R Raj Lal

          Ok lets me be the first to ask a maths question Find a number which 1. divided by 10 gives a remainder 9 2. divided by 9 gives remainder 8 --- --- so on till divided by 2 gives a remainder 1 Any one ?

          Omit Needless Words - Strunk, William, Jr.


          Online Project Management
          Universal DBA | Ajax Rating | ExplorerTree

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          J Offline
          JenovaProject
          wrote on last edited by
          #19

          10! - 1 = 3628799. Its 1 less than a multiple of 1, 2, 3 ... 10.

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          • J JenovaProject

            10! - 1 = 3628799. Its 1 less than a multiple of 1, 2, 3 ... 10.

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            Ingo
            wrote on last edited by
            #20

            ((3628799 + 1) / 10) / (2 * 3 * 4 * 6) + (9 - 7 + 8 - 10) + 1 = 2519. ;)

            ------------------------------ PROST Roleplaying Game War doesn't determine who's right. War determines who's left.

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            • R Raj Lal

              Ok lets me be the first to ask a maths question Find a number which 1. divided by 10 gives a remainder 9 2. divided by 9 gives remainder 8 --- --- so on till divided by 2 gives a remainder 1 Any one ?

              Omit Needless Words - Strunk, William, Jr.


              Online Project Management
              Universal DBA | Ajax Rating | ExplorerTree

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              Bassam Abdul Baki
              wrote on last edited by
              #21

              x = (i - 1) (mod i), 2 ≤ i ≤ 10. Thus, x = LCM(2, 3, 4, 5, 6, 7, 8, 9, 10) * k + LCM(2, 3, 4, 5, 6, 7, 8, 9, 10) - 1 LCM(2, 3, 4, 5, 6, 7, 8, 9, 10) = LCM(5, 7, 8, 9) = 23.32.5.7 = 2520. Thus, x = 2520k + 2519. min(x) = 2519. I had to redo it since I did it backwards.


              "People who want to share their religious views with you almost never want you to share yours with them." - Anonymous Web - Blog - RSS - Math - LinkedIn

              Last modified: Thursday, July 27, 2006 12:08:26 PM --

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              • R Raj Lal

                Ok lets me be the first to ask a maths question Find a number which 1. divided by 10 gives a remainder 9 2. divided by 9 gives remainder 8 --- --- so on till divided by 2 gives a remainder 1 Any one ?

                Omit Needless Words - Strunk, William, Jr.


                Online Project Management
                Universal DBA | Ajax Rating | ExplorerTree

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                Kacee Giger
                wrote on last edited by
                #22

                I know I'm a little late (and a valid solution has already been given), but no real explanation has been made. You first need to find a number that is a multiple of all these multiples (10 * 9, 9 * 8, etc), then one less than that will give the proper remainders. So, to find the least common multiple, first break these into primes: 10 * 9 = 2 * 3 * 3 * 5, 9 * 8 = 2 * 2 * 2 * 3 * 3, 8 * 7 = 2 * 2 * 2 * 7, etc. Take out what is unique for each to get 2 * 2 * 2 * 3 * 3 * 5 * 7 = 2520. So, one answer (though you already know) to the original problem is 2519.

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                • J Jon Sagara

                  N(1) = 2519 N(2) = 2519 + 2520 = 5039 N(3) = 2519 + 2520 + 2520 = 7559 N(4) = 2519 + 2520 + 2520 + 2520 = 10079 ... N(n) = 2519 + (n - 1)*(2520) No idea what the heck it means, though. Care to enlighten us mathematically-challenged folks?

                  Jon Sagara When I grow up, I'm changing my name to Joe Kickass! My Site | My Blog | My Articles

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                  Raj Lal
                  wrote on last edited by
                  #23

                  its the LCM of all the numbers (2520) - 1

                  Omit Needless Words - Strunk, William, Jr.


                  Online Project Management
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                  • K Kacee Giger

                    I know I'm a little late (and a valid solution has already been given), but no real explanation has been made. You first need to find a number that is a multiple of all these multiples (10 * 9, 9 * 8, etc), then one less than that will give the proper remainders. So, to find the least common multiple, first break these into primes: 10 * 9 = 2 * 3 * 3 * 5, 9 * 8 = 2 * 2 * 2 * 3 * 3, 8 * 7 = 2 * 2 * 2 * 7, etc. Take out what is unique for each to get 2 * 2 * 2 * 3 * 3 * 5 * 7 = 2520. So, one answer (though you already know) to the original problem is 2519.

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                    User 12346520
                    wrote on last edited by
                    #24

                    thanks: https://movied.org

                    1 Reply Last reply
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                    • B Bassam Abdul Baki

                      x = (i - 1) (mod i), 2 ≤ i ≤ 10. Thus, x = LCM(2, 3, 4, 5, 6, 7, 8, 9, 10) * k + LCM(2, 3, 4, 5, 6, 7, 8, 9, 10) - 1 LCM(2, 3, 4, 5, 6, 7, 8, 9, 10) = LCM(5, 7, 8, 9) = 23.32.5.7 = 2520. Thus, x = 2520k + 2519. min(x) = 2519. I had to redo it since I did it backwards.


                      "People who want to share their religious views with you almost never want you to share yours with them." - Anonymous Web - Blog - RSS - Math - LinkedIn

                      Last modified: Thursday, July 27, 2006 12:08:26 PM --

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                      User 12346520
                      wrote on last edited by
                      #25

                      thanks: https://movied.org

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                      • I Ingo

                        ((3628799 + 1) / 10) / (2 * 3 * 4 * 6) + (9 - 7 + 8 - 10) + 1 = 2519. ;)

                        ------------------------------ PROST Roleplaying Game War doesn't determine who's right. War determines who's left.

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                        User 12346520
                        wrote on last edited by
                        #26

                        thanks: https://movied.org

                        1 Reply Last reply
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                        • J JenovaProject

                          10! - 1 = 3628799. Its 1 less than a multiple of 1, 2, 3 ... 10.

                          U Offline
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                          User 12346520
                          wrote on last edited by
                          #27

                          thanks: https://movied.org

                          1 Reply Last reply
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                          • R Raj Lal

                            its the LCM of all the numbers (2520) - 1

                            Omit Needless Words - Strunk, William, Jr.


                            Online Project Management
                            Universal DBA | Ajax Rating | ExplorerTree

                            U Offline
                            U Offline
                            User 12346520
                            wrote on last edited by
                            #28

                            thanks: https://movied.org

                            1 Reply Last reply
                            0
                            • L leppie

                              Some other interesting and useless observations:

                              1*2*3*4*5*6*7*8*9 is divisible by 2520 = 144
                              2520 is divisible by 2 * 3 * 5 * 7 = 12 (product of prime 1 - 9)
                              4 * 6 * 8 * 9 is divisible by 144 = 12 (product of 'non' prime 1 - 9)

                              :doh:

                              **

                              xacc.ide-0.2.0.50 - now with partial MSBuild support!

                              **

                              U Offline
                              U Offline
                              User 12346520
                              wrote on last edited by
                              #29

                              thanks: https://movied.org

                              1 Reply Last reply
                              0
                              • L leppie

                                Jon Sagara wrote:

                                N(n) = 2519 + (n - 1)*(2520)

                                N(n) = (n * 2520) - 1 = 2520n - 1

                                **

                                xacc.ide-0.2.0.50 - now with partial MSBuild support!

                                **

                                U Offline
                                U Offline
                                User 12346520
                                wrote on last edited by
                                #30

                                thanks: https://movied.org

                                1 Reply Last reply
                                0
                                • J Jon Sagara

                                  N(1) = 2519 N(2) = 2519 + 2520 = 5039 N(3) = 2519 + 2520 + 2520 = 7559 N(4) = 2519 + 2520 + 2520 + 2520 = 10079 ... N(n) = 2519 + (n - 1)*(2520) No idea what the heck it means, though. Care to enlighten us mathematically-challenged folks?

                                  Jon Sagara When I grow up, I'm changing my name to Joe Kickass! My Site | My Blog | My Articles

                                  U Offline
                                  U Offline
                                  User 12346520
                                  wrote on last edited by
                                  #31

                                  thanks: https://movied.org

                                  1 Reply Last reply
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                                  • P Paul Conrad

                                    Judah Himango wrote:

                                    Voila, cool little WinForms program that solves it. :cool:

                                    That's cool. Mine is just a plain boring console app :->


                                    I'd like to help but I am too lazy to Google it for you.

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                                    User 12346520
                                    wrote on last edited by
                                    #32

                                    thanks: https://movied.org

                                    1 Reply Last reply
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                                    • J Judah Gabriel Himango

                                      Quartz... wrote:

                                      It's the journey, not the destination

                                      Very true. I actually had fun writing a little piece of code to solve it, though, so it was the journey even still. :) I added some more code that added each match to a list box on a Windows Form. Then, after seeing how it froze up the UI, I did it on a background thread. Still, the UI thread would get flooded with matches, almost preventing it from painting, so I further chagned the code to only update during app idle. Voila, cool little WinForms program that solves it. :cool:

                                      Tech, life, family, faith: Give me a visit. I'm currently blogging about: Messianic Instrumentals (with audio) The apostle Paul, modernly speaking: Epistles of Paul Judah Himango

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                                      User 12346520
                                      wrote on last edited by
                                      #33

                                      thanks: https://movied.org

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                                      • R Raj Lal

                                        Judah Himango wrote:

                                        I kind of cheated though

                                        well thats ok , and of course there are more numbers but the fun is when you deduce how to do it It's the journey, not the destination

                                        Omit Needless Words - Strunk, William, Jr.


                                        Online Project Management
                                        Universal DBA | Ajax Rating | ExplorerTree

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                                        User 12346520
                                        wrote on last edited by
                                        #34

                                        thanks: https://movied.org

                                        1 Reply Last reply
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                                        • P Paul Conrad

                                          leppie wrote:

                                          So there are more than one of these. I wonder if its some kind of series...

                                          Take a look at the modification of Judah's code that I posted. Your number is one of the numbers that come up :)


                                          I'd like to help but I am too lazy to Google it for you.

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                                          User 12346520
                                          wrote on last edited by
                                          #35

                                          thanks: https://movied.org

                                          1 Reply Last reply
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