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 so easy by NK)
In fact, counting from the decimal makes your number
AAAAx1AAAA
x=9 gives 91, which is divisible by 13. Thus, we both get the same answer (9), but your approach is MUCH easier.

Posted by NK
on 20040210 19:03:12 