Jakow Trachtenberg was a Jewish mathematician who developed the mental calculation techniques called the Trachtenberg system. He was born in Odessa, the Russian empire in 1988 and worked as an engineer in the Obukhov arms factory. He was a dedicated pacifist and instrumental in organising the Society of Good Samaritans when the First World War broke out. After the Russian revolutions of 1917, Trachtenberg fled to the Weimar Republic where he was later critical of Nazi policies and imprisoned in a concentration camp during World War II. He developed his system of mathematics during his imprisonment. He died in 1953.
Books by Jakow Trachtenberg
The Trachtenberg Speed System of Basic Mathematics
Do high-speed, complicated arithmetic in your head using the Trachtenberg Speed System.