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The Trachtenberg System is a system of rapid mental calculation . The system consists of a number of readily memorized operations that allow one to perform arithmetic computations very quickly. It was developed by the Russian Jewish engineer Jakow Trachtenberg in order to keep his mind occupied while being held in a Nazi concentration camp . The rest of this article presents some of the methods devised by Trachtenberg. The most important algorithms are the ones for general multiplication, division and addition [ citation needed ] .