Odds and evens

Odds and evens, also known as swords, choosies, pick, odds-on poke, or bucking up, is a hand game played between two people, used to decide an issue. This zero-sum game, a variation of the ancient Morra and par-impar, is played internationally, especially among children.

The individuals prepare by deciding who will be assigned odds and who will be evens. Then, one or both people say "One, two, three, shoot!!" or "one, strikes, three, shoot!" As the word "shoot" is said, the two people quickly and simultaneously thrust a fist into the center, extending either an index finger, or both the middle and index finger, indicating one or two. The sum total of fingers displayed is either odd or even. If the result is odd, then the person who called odds is the victor, and can decide the issue as he or she sees fit. Often, the participants continue to shoot for a best two out of three.

From a game-theoretic perspective, the game is equivalent to Matching pennies. See that article for analysis of the strategies and chances of winning.

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