Adding machine

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An adding machine is a class of mechanical calculator, usually specialized for bookkeeping calculations. Consequently, the earliest adding machines were often designed to read in particular currencies. Adding machines were ubiquitous office equipment in developed countries for most of the twentieth century. They were phased out in favor of electronic calculators in the 1970s and by personal computers beginning in about 1985. Blaise Pascal and Wilhelm Schickard were the two original inventors of the mechanical calculator in 1642. For Pascal, this was an adding machine that could perform additions and subtractions directly and multiplication and divisions by repetitions, while Schickard's machine, invented several decades earlier, was less functionally efficient but was supported by a mechanised form of multiplication tables. These two were followed by a series of inventors and inventions leading to those of Thomas de Colmar, who launched the mechanical calculator industry in 1851 when...

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