On the left is a U pentomino.  On the right is an I tromino.

There is a particular shape (holes are permitted) that you can build with three copies of the piece on the left, or with 5 copies of the piece on the right. You may rotate and flip the pieces, but they cannot overlap. What shape can you build?

This puzzle is from: http://skepticsplay.blogspot.com/2010/04/polyomino-equations.html

  • 1
    $\begingroup$ Is the shape allowed to have a hole inside of it? $\endgroup$
    – Alaiko
    Oct 21, 2023 at 9:08
  • $\begingroup$ @Alaiko Yes, holes inside the shape are allowed. $\endgroup$ Oct 21, 2023 at 9:26

1 Answer 1


I think the following would be OK since holes are allowed in the shape.


Using the piece on the left,


Using the piece on the right,



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