What is the biggest 5 digit number such that when multiplied by a single digit, the result is a six digit number, with all digits identical?
111111 = 3*7*11*13*37, so the single digit multiplier will be 3 or 7.
111111/3 = 37037, and the biggest 5 digit multiple of 37037 is 74074
111111/7 = 15873, and the biggest 5 digit multiple of 15873 is 95238
So, 95238 is our answer.
95238 * 7 = 666666
Edited on June 12, 2012, 3:26 pm
Solution (spoiler)
