Before electronic calculators became available in the 70's, the Curta Calculator was considered to be the most efficient portable calculator available. The device boasts 605 intricate parts and it can perform addition, subtraction, multiplication, division, and even square roots without electricity. Perhaps the most interesting bit of info about the device is the man who developed it. Curt Herzstark reconstructed the intricate device from memory while serving time in a Nazi concentration camp. [vcalc]