DPW An Abacus (BC) A mechanical device used for counting. Addition, subtraction, multiplication and division can be performed on a standard abacus. Using the abacus is still taught in Asian schools and still used by shopkeepers in Asia and “Chinatowns” in the USA.
DPW Napier’s Bones (1617) of logarithms and calculate based on relative position of the scales and when bound together created the first slide rule. John Napier’s bones work on the principal