1st CIS 1992 Problem 5 Does there exist a 4-digit integer which cannot be changed into a multiple of 1992 by changing 3 of its digits?
Yes, eg 2251 Solution The only 4 digit multiples of 1992 are: 1992, 3984, 5976, 7968, 9960. All have first digit odd, second digit 9, third digit > 5 and last digit even, so it is easy to find a number which has all digits different from all of them. 1st CIS 1992 © John Scholes jscholes@kalva.demon.co.uk 5 December 2003 Last corrected/updated 5 Dec 03