Two Monks, Same Seven Pieces, One Missing a Foot
Using the same seven tangram pieces arranged two different ways, you can build two monk figures that look almost identical — except one of them is clearly missing a foot. Both figures use every piece, with nothing left over and nothing added. How can removing a foot need no extra material?
Reveal the answer
It's an optical illusion, not a missing-material trick: the second figure's body is subtly larger, silently absorbing the exact area of the 'lost' foot, so both monks have identical total area. This is the classic tangram dissection fallacy popularized by Henry Dudeney in his puzzle collections.
— Henry Dudeney, Amusements in Mathematics — Tangram dissection paradox ('the two monks'), Amusements in Mathematics (1917)
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