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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

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

    Luc Pattyn [My Articles] Nil Volentibus Arduum

    M Offline
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    Manfred Rudolf Bihy
    wrote on last edited by
    #11

    Stating the obvious! 5+ :-D :thumbsup:

    "With sufficient thrust, pigs fly just fine."

    Ross Callon, The Twelve Networking Truths, RFC1925

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    • R riced

      Look at what I said - add 5 or 10. If a number is divisible by 5 it must end in 5 or 0 - that's primary school arithmetic. If you don't believe me write out the 5 times table for the numbers 1 to 20.

      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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      stephen darling
      wrote on last edited by
      #12

      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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      • L Luc Pattyn

        David1987 wrote:

        except zero

        :confused::confused::confused:

        Luc Pattyn [My Articles] Nil Volentibus Arduum

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        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.

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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

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                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

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                  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.

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                    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

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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.

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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

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                                  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

                                      M Offline
                                      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.

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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

                                          F Offline
                                          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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