The Curta is a small, hand-cranked mechanical calculator introduced by Curt Herzstark in 1948. It can be used to perform addition, subtraction, multiplication, division, and (with more difficulty) square roots and other operations.
The Curta's design is a descendant of Gottfried Leibniz's Stepped Reckoner and Thomas's Arithmometer, accumulating values on cogs, which are added or complemented by a stepped drum mechanism. It has an extremely compact design: a small cylinder that fits in the palm of the hand.
Curtas were considered the best portable calculators available until they were displaced by electronic calculators in the 1970s.