Topic summary
Peasant multiplication
Extracted from the Wikipedia article Ancient Egyptian multiplication.
Russian peasant multiplication
In the Russian peasant method, the powers of two in the decomposition of the multiplicand are found by writing it on the left and progressively halving the left column, discarding any remainder, until the value is 1 (or −1, in which case the eventual sum is negated), while doubling the right column as before. Lines with even numbers on the left column are struck out, and the remaining numbers on the right are added together.