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Comptometer
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===Origins=== [[Image:Macaronibox.jpg|thumb|right|<div align="center">The macaroni box (1885)</div>]] The comptometer is the direct descendant of the key-driven machine of Thomas Hill<ref>[https://patents.google.com/patent/US18692 Hill's Arithmometer patent]</ref> patented in the United States in 1857 and of the [[Pascaline]] invented by [[Blaise Pascal]] in France in 1642. By just replacing the input wheels of the Pascaline by the columns of keys of Hill's machine, the comptometer was invented. Addition is performed exactly the same way, and both the Pascaline and the Comptometer make use of the [[Method of complements|9's complement]] method for subtraction, but in the case of the comptometer it is the operator who must choose the right keys for the [[subtrahend]] (each key has its 9's complement written in miniature letter next to it).
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