Four copies of the P pentomino pictured below can easily be placed in a 5x5 square without overlapping.

+--+--+--+
|  |  |  |
+--+--+--+
|  |  |
+--+--+

Prove it is impossible to put 5 copies in a 5x5 square without overlapping.

Which of the other 11 pentominoes can be included with four P pentominoes such that all five can be placed in a 5x5 square?

The official solution is interesting and nicely explained. 

Edited on March 5, 2016, 5:05 pm

Posted by armando on 2016-03-05 17:02:41