Curta Calculating Machines

The Curta Calculators were invented and patented by Curt Herzstark in 1938. This single drum replaced the multiple drums of contemporary calculators, and it enabled addition and subtraction through nines complement math, essentially subtracting by adding. He was a watchmakers apprentice and that may explain all 605 intricate parts that make up the Curta. In 1943, Herzstark was placed in the Buchenwald concentration camp where the Nazis forced him to continue his research on his invention. Curtas were known to be the best portable calculators available until they were displaced by electronic calculators in the 1970's.