Problem:
Suppose are (not necessarily distinct) nonzero digits in base ten for which
- the four-digit number is divisible by , and
- the four-digit number is divisible by .
Compute the four-digit number .
Problem:
Suppose are (not necessarily distinct) nonzero digits in base ten for which
- the four-digit number is divisible by , and
- the four-digit number is divisible by .
Compute the four-digit number .
Solution:
Let and . Then and , so . We can now exhaustively list the possible cases for :
- if , then which is not possible;
- if , then , which gives and ;
- if , then which is not possible;
- if , then which is not possible.
Hence, we must have , so .