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## complex multiplication function in Haskell

 Hi there, The number 354162 has 6 digits and contains all digits from 1 to 6, and it can be considered as a multiplication of 3 * 54 = 162.  so what I need is a function that will take all the real number and return the number that can be split as above,  354162  .. 3 * 54 = 162   I have no idea how to do such a thing! any help!  _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafeOnly members subscribed via the mailman list are allowed to post.
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## Re: complex multiplication function in Haskell

 Maybe just enumerate the possibilities   1 * 1 = 1 => 111 1 * 2 = 2 => 112 1 * 3 = 3 => 113 ... 2 * 1 = 2 => 212 ... From: Haskell-Cafe [mailto:[hidden email]] On Behalf Of Mahmoud MuradSent: Wednesday, April 26, 2017 8:03 AMTo: [hidden email]Subject: [Haskell-cafe] complex multiplication function in Haskell Hi there,  The number 354162 has 6 digits and contains all digits from 1 to 6, and it can be considered as a multiplication of 3 * 54 = 162.   so what I need is a function that will take all the real number and return the number that can be split as above,   354162  .. 3 * 54 = 162    I have no idea how to do such a thing! any help!  _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafeOnly members subscribed via the mailman list are allowed to post.
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## Re: complex multiplication function in Haskell

 In reply to this post by Mahmoud Murad > On 27/04/2017, at 12:02 AM, Mahmoud Murad <[hidden email]> wrote: > > Hi there, > The number 354162 has 6 digits and contains all digits from 1 to 6, and it can be considered as a multiplication of 3 * 54 = 162.   > so what I need is a function that will take all the real number and return the number that can be split as above,   > 354162  .. 3 * 54 = 162   > I have no idea how to do such a thing! any help! Start by spelling out just what the conditions are. - Are you looking specifically for 6-digit numbers or could it be more?   (Because you say "ALL the real number[s]". - Are you sure you want REAL numbers and not INTEGERS? One way to read what you have written is  - find a permutation [a,b,c,d,e,f] of [1,2,3,4,5,6]  - such that a*(b*10+c) == (d*10+e)*10+f. There are only 6! = 720 permutations of six digits, so not a lot to check.  For a computer program, I'd just code that. We can restructure this as - find three different digits 1 <= a,b,c <= 6 - compute def = a*(b*10+c) - check that the digits of def are all 1..6 and all   different and different from a,b,c. There are 120 cases to check here. As it happens, Data.List provides permutations Prelude> import Data.List Prelude Data.List> permutations [1..3] [[1,2,3],[2,1,3],[3,2,1],[2,3,1],[3,1,2],[1,3,2]] Prelude Data.List> length (permutations [1..6]) 720 You can combine this with a list comprehension to get the numbers you want. _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafeOnly members subscribed via the mailman list are allowed to post.