Move a single matchstick so that there are six squares. Each matchstick’s entire length must be part of at least one square.
There are three solutions, including the mirror image of the second shown solution. Each solution creates four small squares and two large overlapping ones.
Editor's Note (1/29/26): This puzzle was updated after publishing to clarify a typical constraint for matchstick puzzles.
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This puzzle originally appeared in Spektrum der Wissenschaft and was reproduced with permission.