In assembling our previous collection of 25 problems involving the number 25, we had an extra ready to go if needed. In fact, there are three jigsaw-type puzzles we present below. They involve partial sets of the 12 pentomino pieces made from five squares. The full set is shown at right. You are asked to assemble each set into a five by five square.

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Extremely gifted people may be able to solve these puzzles mentally, but I wouldn’t attempt it myself. If you want to manipulate the pieces, and make up new puzzles of your own, here is a link to a plan for them. Boxboard or even manila folders should make a sturdy enough set.