Place the numbers 1-9 in the boxes so that the difference of each pair of numbers joined by a line is at least three. The number 8 has already been placed.

Rows from the top: 8-3-7  2-6-9  5-1-4

The two boxes in the center could be either 6,9 or 9,6; else these are the only solutions.

  

 

Posted by ed bottemiller on 2010-08-04 13:33:44