Twenty-two is a pentagonal number.
When cutting a circle with just six line segments, the maximum number of pieces that can be so created is 22.
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Although, silver coins with central pentagonal punch mark have been reported4, detailed metallurgical analysis of this series of coins has not yet been published.
Square-rectangular, pentagonal and hexagonal coins
Special-edition klippe coins to commemorate the 10th anniversary of the National Bank of Poland putting a new coinage system into circulation were struck by the Polish State Mint.
 See also: Triangular, Unit, Scrip, Square, Ten
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