N is a 3x3 square grid which is constituted by using each of the digits from 1 to 9 exactly once.
Determine the probability that the first digit minus the second digit plus the third digit in each row (reading left to right), each column (reading top to bottom), and each main diagonal (reading top to bottom) of N is the same.
(In reply to
Analytical Solution (spoiler) by Steve Herman)
Congratulations.
I personally prefer an analytical but sometimes they are not evident.
It wasn't until after running my program that I realised that the configuration of the "15 magic square" is intact other than the extreme cells of the middle horizontal row and vertical column are swapped.

Posted by brianjn
on 20091206 05:26:37 