The arithmometer (French: arithmomètre) was the first digital mechanical calculator strong enough and reliable enough to be used daily in an office environment. This calculator could ...
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add and subtract two numbers directly and could perform long multiplications and divisions effectively by using a movable accumulator for the result.
Patented in France by Thomas de Colmar in 1820 and manufactured from 1851 to 1915,[citation needed] it became the first commercially successful mechanical calculator. Its sturdy design gave it a strong reputation for reliability and accuracy and made it a key player in the move from human computers to calculating machines that took place during the second half of the 19th century.