A number of 50 digits has all its digits equal to 1 except the 26th digit. If the number is divisible by 13, then find the digit in the 26th place.

(In reply to re(6): solution by SilverKnight)

SilverKnight:
Your opinion carries weight with me as you appear to be the star solver on this site. None of the hyperlinks I could find on "mod m" are suitable to pass on here. The books I could find aren't either. Perhaps you know of a hyperlink or book that is suitable. I know that I am done trying to explain the concept to novices. For the more advanced, I highly recommend a gander at the first sections of Gauss' Disquistiones Arithmeticae in the Clarke translation.
~Richard

Posted by Richard on 2003-11-23 12:24:27