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  4. How do I generate a number divisable by 5, and check it?

How do I generate a number divisable by 5, and check it?

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  • L Luc Pattyn

    David1987 wrote:

    except zero

    :confused::confused::confused:

    Luc Pattyn [My Articles] Nil Volentibus Arduum

    D Offline
    D Offline
    David1987
    wrote on last edited by
    #13

    It depends on the definition of divisibility that you use. Zero can also be divisible by anything, if you use an other definition.

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    • R riced

      Generate a four digit random number, multiply it by 10, add 5 (or 10). The result will be divisible by 5.

      Regards David R --------------------------------------------------------------- "Every program eventually becomes rococo, and then rubble." - Alan Perlis The only valid measurement of code quality: WTFs/minute.

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      Simon Bang Terkildsen
      wrote on last edited by
      #14

      you shouldn't add 5 or 10 but 5 or 0. In the case the random generator provides 9999 then you would get 9999 * 10 + 10 = 99990 + 10 = 100000 six digits

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      • D David1987

        It depends on the definition of divisibility that you use. Zero can also be divisible by anything, if you use an other definition.

        L Offline
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        Luc Pattyn
        wrote on last edited by
        #15

        BS.

        zero times x equals zero, no matter what (finite) value x has.

        so (the right side's) zero is divisible by x, and the result is (the left side's) zero. If I hold 10 pies, 5 bacon sandwiches, and zero glasses of milk, I have no problem distributing them evenly to 5 people. Next you'll state you could also redefine 5, so it no longer divides itself. :)

        Luc Pattyn [My Articles] Nil Volentibus Arduum

        OriginalGriffO D 2 Replies Last reply
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        • L Luc Pattyn

          BS.

          zero times x equals zero, no matter what (finite) value x has.

          so (the right side's) zero is divisible by x, and the result is (the left side's) zero. If I hold 10 pies, 5 bacon sandwiches, and zero glasses of milk, I have no problem distributing them evenly to 5 people. Next you'll state you could also redefine 5, so it no longer divides itself. :)

          Luc Pattyn [My Articles] Nil Volentibus Arduum

          OriginalGriffO Offline
          OriginalGriffO Offline
          OriginalGriff
          wrote on last edited by
          #16

          Luc Pattyn wrote:

          Next you'll state you could also redefine 5, so it no longer divides itself.

          It doesn't. There are only four bacon sandwiches left... :laugh:

          Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together. Manfred R. Bihy: "Looks as if OP is learning resistant."

          "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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          • L Luc Pattyn

            BS.

            zero times x equals zero, no matter what (finite) value x has.

            so (the right side's) zero is divisible by x, and the result is (the left side's) zero. If I hold 10 pies, 5 bacon sandwiches, and zero glasses of milk, I have no problem distributing them evenly to 5 people. Next you'll state you could also redefine 5, so it no longer divides itself. :)

            Luc Pattyn [My Articles] Nil Volentibus Arduum

            D Offline
            D Offline
            David1987
            wrote on last edited by
            #17

            Nope. You seem to think that that is the only definition of divisibility. I did not personally redefine anything. There is no natural number n such that 0/x=n so no x evenly divides 0. If you use the definition with integers instead of natural numbers, everything divides zero. Also, the prime factorization of zero is empty.

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            • S stephen darling

              Hi. First, how would I create a random number, and then add the last digit, so that it is divisable by 5? the number should always be 5 digits long. Second, how do I check it, I think I need to do something like...

              if (int x MOD 5 ==0)

              Or something like that. The first step is the most important though. Thank you, Steve

              L Offline
              L Offline
              Lost User
              wrote on last edited by
              #18

              Didn't you already post this in the Q&A and get an answer to it?? Generating numbers to the multiple of 5?[^]

              Computers have been intelligent for a long time now. It just so happens that the program writers are about as effective as a room full of monkeys trying to crank out a copy of Hamlet.

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              • D David1987

                Nope. You seem to think that that is the only definition of divisibility. I did not personally redefine anything. There is no natural number n such that 0/x=n so no x evenly divides 0. If you use the definition with integers instead of natural numbers, everything divides zero. Also, the prime factorization of zero is empty.

                L Offline
                L Offline
                Luc Pattyn
                wrote on last edited by
                #19

                natural numbers are the ordinary counting numbers 1, 2, 3, ... (sometimes zero is also included) is what Wikipedia[^] offers as a definition. Now you can choose: either you include zero and you are allowed to use it at both sides of your 0/x=n, or you exclude it (and then your "except zero" remark that started all this is completely irrelevant). :doh:

                Luc Pattyn [My Articles] Nil Volentibus Arduum

                D 1 Reply Last reply
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                • OriginalGriffO OriginalGriff

                  Luc Pattyn wrote:

                  Next you'll state you could also redefine 5, so it no longer divides itself.

                  It doesn't. There are only four bacon sandwiches left... :laugh:

                  Real men don't use instructions. They are only the manufacturers opinion on how to put the thing together. Manfred R. Bihy: "Looks as if OP is learning resistant."

                  L Offline
                  L Offline
                  Luc Pattyn
                  wrote on last edited by
                  #20

                  Sorry for the late reply, I have been off-line this evening, I have another tournament going on this week. I trust all bacon sandwiches have magically disappeared by now, and so the problem got solved? :)

                  Luc Pattyn [My Articles] Nil Volentibus Arduum

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                  • S stephen darling

                    riced wrote:

                    If a number is divisible by 5 it must end in 5 or 0

                    Yes; I was getting confused with the coding issue not the actual math.

                    riced wrote:

                    that's primary school arithmetic.

                    I know, I am a Biomedical Scientist.

                    riced wrote:

                    If you don't believe me write out the 5 times table for the numbers 1 to 20.

                    I do believe you. Like I said, it was the coding side of things. However, it is my fault the way I explained myself, it did indeed look as though I didn’t understand the math itself, and I certainly was not questioning you answer. Sorry if it came across that way, and thank you. Kind Regards, Stephen

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                    Mycroft Holmes
                    wrote on last edited by
                    #21

                    Your confusion did lead me to think - how old is this guy, doesn't understand primary grade maths :-D

                    Never underestimate the power of human stupidity RAH

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                    • L Luc Pattyn

                      natural numbers are the ordinary counting numbers 1, 2, 3, ... (sometimes zero is also included) is what Wikipedia[^] offers as a definition. Now you can choose: either you include zero and you are allowed to use it at both sides of your 0/x=n, or you exclude it (and then your "except zero" remark that started all this is completely irrelevant). :doh:

                      Luc Pattyn [My Articles] Nil Volentibus Arduum

                      D Offline
                      D Offline
                      David1987
                      wrote on last edited by
                      #22

                      Yes but that's precisely the point, you can choose.

                      1 Reply Last reply
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                      • D David1987

                        Generate a random integer in [2000, 19999] and multiply it by 5. The result will always be in [10000, 99999] (ie 5 decimal digits) and be divisible by 5 (by construction)

                        int yourNumber = 5 * rand.Next(2000, 20000); // remember the max-bound is exclusive
                        if (yourNumber % 5 != 0)
                        Console.WriteLine("the universe is wrong");

                        And make sure you reuse a single instance of Random, if you create new ones the result won't be random. [/spoon feeding]

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                        stephen darling
                        wrote on last edited by
                        #23

                        David1987 wrote:

                        And make sure you reuse a single instance of Random,

                        How exactly do I ensure that I am doing this? I am using rand a number of times, and although I get different values, it does appear that they are very simular. Regards, Stephen

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                        • D David1987

                          Nope. You seem to think that that is the only definition of divisibility. I did not personally redefine anything. There is no natural number n such that 0/x=n so no x evenly divides 0. If you use the definition with integers instead of natural numbers, everything divides zero. Also, the prime factorization of zero is empty.

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                          B Offline
                          BobJanova
                          wrote on last edited by
                          #24

                          That is a stupid definition. It would also indicate that -10 is not divisible by 5. There may be abstruse mathematical concepts for which it's useful, I suppose, but for normal maths it is nonsense.

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                          • S stephen darling

                            Does this mean that no matter what number I generate, it will always have to end in 5? e.g. All these numbers are divisable by 5

                            39485
                            99045
                            12095
                            49385
                            99335

                            However, I was under the impression I could generate numbers that would be divisable by 5, but not end in 5? Is this wrong? Regards, Stephen

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                            Gary Wheeler
                            wrote on last edited by
                            #25

                            All integers evenly divisible by 5 must end in either 5 or 0 when expressed in base 10. This is basic math.

                            Software Zen: delete this;

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                            • S stephen darling

                              Hi. First, how would I create a random number, and then add the last digit, so that it is divisable by 5? the number should always be 5 digits long. Second, how do I check it, I think I need to do something like...

                              if (int x MOD 5 ==0)

                              Or something like that. The first step is the most important though. Thank you, Steve

                              T Offline
                              T Offline
                              Tom Chantler
                              wrote on last edited by
                              #26

                              Is this a joke question? Generate a four digit number and add an extra number to the end, being either 5 or 0. Then don't check it because it will be correct!!! e.g. 4678; add 5 on the end to give 46785.

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                              • S stephen darling

                                Hi. First, how would I create a random number, and then add the last digit, so that it is divisable by 5? the number should always be 5 digits long. Second, how do I check it, I think I need to do something like...

                                if (int x MOD 5 ==0)

                                Or something like that. The first step is the most important though. Thank you, Steve

                                P Offline
                                P Offline
                                Paulo_JCG
                                wrote on last edited by
                                #27

                                Random random = new Random(); return (random.Next(17999) + 2000) * 5; this gives a number divisable by 5 between 10000 and 99995

                                Paulo Gomes Over and Out :D

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                                • S stephen darling

                                  riced wrote:

                                  If a number is divisible by 5 it must end in 5 or 0

                                  Yes; I was getting confused with the coding issue not the actual math.

                                  riced wrote:

                                  that's primary school arithmetic.

                                  I know, I am a Biomedical Scientist.

                                  riced wrote:

                                  If you don't believe me write out the 5 times table for the numbers 1 to 20.

                                  I do believe you. Like I said, it was the coding side of things. However, it is my fault the way I explained myself, it did indeed look as though I didn’t understand the math itself, and I certainly was not questioning you answer. Sorry if it came across that way, and thank you. Kind Regards, Stephen

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                                  M Offline
                                  mmwlada
                                  wrote on last edited by
                                  #28

                                  stephen.darling wrote:

                                  riced wrote:

                                  that's primary school arithmetic.

                                  I know, I am a Biomedical Scientist.

                                  You are NOT a scientist. A scinetist knows elementary math. You should be ashamed of yourself.

                                  There can be only one.

                                  S realJSOPR N 3 Replies Last reply
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                                  • M mmwlada

                                    stephen.darling wrote:

                                    riced wrote:

                                    that's primary school arithmetic.

                                    I know, I am a Biomedical Scientist.

                                    You are NOT a scientist. A scinetist knows elementary math. You should be ashamed of yourself.

                                    There can be only one.

                                    S Offline
                                    S Offline
                                    stephen darling
                                    wrote on last edited by
                                    #29

                                    mmwlada wrote:

                                    You are NOT a scientist. A scinetist knows elementary math. You should be ashamed of yourself.

                                    How dare you! I may be a beginner in the programming world, but to be spoken to in this way from someone who does not know me is extremely rude! I am indeed a scientist, registered in the UK as a practising biomedical scientist, not that I need to explain myself to you! As for the math, if you took the time to read through the post, you would see that I simply explained myself wrong, and it was the programming that I was struggling with, and not the math. As for being ashamed of myself; I do not know what your problem is, but believe me, I have nothing to be ashamed of, and could now go on to say allot about, and to you, however, I will refrain! Stephen

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                                    • S stephen darling

                                      riced wrote:

                                      If a number is divisible by 5 it must end in 5 or 0

                                      Yes; I was getting confused with the coding issue not the actual math.

                                      riced wrote:

                                      that's primary school arithmetic.

                                      I know, I am a Biomedical Scientist.

                                      riced wrote:

                                      If you don't believe me write out the 5 times table for the numbers 1 to 20.

                                      I do believe you. Like I said, it was the coding side of things. However, it is my fault the way I explained myself, it did indeed look as though I didn’t understand the math itself, and I certainly was not questioning you answer. Sorry if it came across that way, and thank you. Kind Regards, Stephen

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                                      F Offline
                                      FunkySteve
                                      wrote on last edited by
                                      #30

                                      Actually, every number is divisible by 5.

                                      S 1 Reply Last reply
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                                      • F FunkySteve

                                        Actually, every number is divisible by 5.

                                        S Offline
                                        S Offline
                                        stephen darling
                                        wrote on last edited by
                                        #31

                                        FunkySteve wrote:

                                        Actually, every number is divisible by 5

                                        True. Again, my fault for not explaining properly. I meant a modulus of zero, so that 13285 MOD 5 = 0 Got it all sorted now, thanx to most people, disregarding one perticular ignorant comment :confused: Thank you, Steve

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                                        • L Luc Pattyn

                                          a random multiple of five is bound to be five times some other random number. :omg:

                                          Luc Pattyn [My Articles] Nil Volentibus Arduum

                                          F Offline
                                          F Offline
                                          Fabio Franco
                                          wrote on last edited by
                                          #32

                                          I'd say you're stating the obvious, but then, I remember when I was very young and inexperienced and I couldn't see stuff like this. So, it's not always obvious as one might think. You got my five.

                                          "To alcohol! The cause of, and solution to, all of life's problems" - Homer Simpson

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