The Curta is a small mechanical calculator developed by Curt Herzstark. The Curta’s design is a descendant of Gottfried Leibniz’s Stepped Reckoner and Charles Thomas’ 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.
The Curta was introduced in 1947, the last models were produced in 1970. It supported 11 to 15 digits making it even more accurate than most simple electronic models today.
Curtas were considered the best portable calculators available until they were displaced by electronic calculators in the 1970s.
The instructions and exercises herein apply both to CURTA model I (8 x 6 x 11 digits) and CURTA model II (11 x 8 x 15 digits). These two models being identical but for their capacity, it has been deemed sufficient to represent only CURTA model I on the illustrations.