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 November 2nd, 2017, 04:06 PM #1 Newbie   Joined: Nov 2017 From: rasht iran Posts: 4 Thanks: 0 how we can guess a last number from a 4number? hello guys. always i has hate from math but a persion asked a puzzle from me! i can not understand he how can guess this ! for more pls read mt next... ( sorry for poor english - i hope you undestand me) he told me write a 4number like 4321 and next write from back 1234 now do 4321 - 1234 and find answer. 4321-1234= 3087 he told me now say me 3 first number from your answer. i told 308 and he told its 3087!!! for new example: i did 9345- 5439= 3906 i and say 390* . but he know what is * !!!! he guess * is 6 !!!! but he with what algorithm can find it ? with what algorithm i can find number of 4 fom a 4number? ------------------------------------------ thanks for your help, i am wait for give a good answer from you. Last edited by edrisdolati; November 2nd, 2017 at 04:09 PM.
 November 2nd, 2017, 05:44 PM #2 Senior Member     Joined: Sep 2015 From: USA Posts: 2,200 Thanks: 1156 what would you do if the reversed number is larger than the original? Thanks from edrisdolati
November 3rd, 2017, 01:45 AM   #3
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Joined: Nov 2017
From: rasht iran

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Quote:
 Originally Posted by romsek what would you do if the reversed number is larger than the original?
i not know really , dears anyone not know thai puzzle?

 November 3rd, 2017, 01:46 AM #4 Newbie   Joined: Nov 2017 From: rasht iran Posts: 4 Thanks: 0 i need for today, pls help me thanks www.landscapingarchitect.ir
 November 3rd, 2017, 04:52 AM #5 Newbie   Joined: Mar 2016 From: United Kingdom Posts: 2 Thanks: 1 Your friend is using the idea of Modulus (to base 9). 4321 mod 9 = 1 (4321/9 = 480 rem 1). 4 + 3 + 2 + 1 = 10; 10/9 = 1 rem 1. 1234 mod 9 = 1 (1234/9 = 137 rem 1). Also 1 + 2 + 3 + 4 = 10; 10/9 = 1 rem 1. The difference between the number chosen and that found by reversing its digits will always have modulus 0 to base 9 ie divisible by 9. So, knowing three digits, your friend finds a fourth that brings the total to a multiple of 9. 3 + 0 + 8 = 11, needs 7 to bring it to 18. 3 + 9 + 0 = 12, needs 6 to bring it to 18. Thanks from topsquark
 November 3rd, 2017, 05:52 AM #6 Newbie   Joined: Nov 2017 From: rasht iran Posts: 4 Thanks: 0 hmmmm game with math jofo dear friend thanks for your help. thanks

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