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
solution by luminita)
Of course Charlie got x=3 because his x is the 26th digit from the left end. You and I got x=9 because our x is the 26th digit from the right end. If you look at the number Charlie shows in Comment 3, and count carefully, the 3 is in the 25th digit from the right end (26th from the left end):
? 11111111111111111111111113111111111111111111111111

Posted by Richard
on 20031231 13:22:37 