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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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  • 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

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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."

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      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.

              B Offline
              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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                G Offline
                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

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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.

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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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                          • 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

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                              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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                              • 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

                                K Offline
                                K Offline
                                Kenneth Kasajian
                                wrote on last edited by
                                #33

                                Is this discussion really taking place? What is this, 3rd grade?

                                ken@kasajian.com / www.kasajian.com

                                S 1 Reply Last reply
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                                • F Fabio Franco

                                  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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                                  L Offline
                                  Luc Pattyn
                                  wrote on last edited by
                                  #34

                                  I tend to state facts, even obvious ones, especially when it seems to OP is missing them somehow. Rather than spoon feeding, I prefer to give a gentle push in the right direction... :)

                                  Luc Pattyn [My Articles] Nil Volentibus Arduum

                                  F 1 Reply Last reply
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                                  • K Kenneth Kasajian

                                    Is this discussion really taking place? What is this, 3rd grade?

                                    ken@kasajian.com / www.kasajian.com

                                    S Offline
                                    S Offline
                                    stephen darling
                                    wrote on last edited by
                                    #35

                                    Kenneth Kasajian wrote:

                                    Is this discussion really taking place? What is this, 3rd grade?

                                    What is everones problem? I asked how to solve a basic math based problem PROGMATICALLY as I am a beginner when it comes to c#, and I am wishing I never bothered asking! Although, there are a number of people who have offered working solutions. Why must people post such a responce as yours? Did your post really help in anyway? Regards, Stephen

                                    K 1 Reply Last reply
                                    0
                                    • L Luc Pattyn

                                      I tend to state facts, even obvious ones, especially when it seems to OP is missing them somehow. Rather than spoon feeding, I prefer to give a gentle push in the right direction... :)

                                      Luc Pattyn [My Articles] Nil Volentibus Arduum

                                      F Offline
                                      F Offline
                                      Fabio Franco
                                      wrote on last edited by
                                      #36

                                      Completely agree, I'm totally against the "gimme codezzzz plz" culture.

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

                                      1 Reply Last reply
                                      0
                                      • 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.

                                        A Offline
                                        A Offline
                                        ARon_
                                        wrote on last edited by
                                        #37

                                        http://mathworld.wolfram.com/EvenNumber.html[^] Note zero is an even number and by definition dividable by two, the answer is just zero. As a recall from calculus I, you can't divide a number by zero but you can divide a number as the devisor approaches zero.

                                        ARon

                                        1 Reply Last reply
                                        0
                                        • 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

                                          U Offline
                                          U Offline
                                          User 7955466
                                          wrote on last edited by
                                          #38

                                          Generate a five digit random number, convert to string, replace the right most digit with 5 (or 0), parse the string back to an int. No need to check as anything ending in 5 or 0 is divible by 5.

                                          M 1 Reply Last reply
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