Place twelve of the numbers 1 to 15 in the grid below such that:
1. The rows (a,b,c,d; e,f,g,h; i,j,k,l) have the same sum.
2. The columns (a,e,i; b,f,j; c,g,k; d,h,l) and the diagonals (a,f,k; b,g,l; c,f,i; d,g,j) all have the same sum.
Note: The rows do not have the same sum as the columns and diagonals.

a|b|c|d
-+-+-+-  
e|f|g|h
-+-+-+-
i|j|k|l

There are precisely 2 solutions (not including rotations and reflections). These are as follows:

Edited on February 16, 2023, 7:56 am

Posted by K Sengupta on 2023-02-16 07:48:05