
Arrange the 12 pieces of a set of pentominoes (see image below)
so that they form holes with the dimension 1x1
The pentominoes must be placed on the same plane
The example below shows 13 of these holes
Michael Lateur shows a solution with 14 holes 
What is the maximum number of holes you can get?
Do you have our excel file to draw your solution? You can download it here.
“FlatPoly2“, a programm by Aad van de Wetering, can be of great assistance when trying to find a solution. It can be downloaded at
his site .