At age 19, Blaise Pascal invented this mechanical calculator to help his father, a tax commissioner, with tedious arithmetic. The Pascaline uses a series of interlocking gears with an ingenious sautoir (gravity-assisted carry mechanism) that propagates tens carries automatically. Each input wheel has digits 0-9; rotating a wheel past 9 trips a lever that advances the next wheel by one. About fifty Pascalines were built, and nine survive today.
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