Friden Marchant Calculator Monroe Curta Curt Herzstark Gottfried Leibniz Stepped Reckoner Thomas Arithmometer Leibniz mechanical calculator
Companies like Friden, Marchant Calculator and Monroe made desktop mechanical calculators from the 1930s that could add, subtract, multiply and divide. In 1948, the Curta was introduced by Austrian inventor Curt Herzstark. It was a small, hand-cranked mechanical calculator and as such, a descendant of Gottfried Leibniz's Stepped Reckoner and Thomas' Arithmometer.
