Trachtenberg system
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
Mental calculation
Mental calculation consists of arithmetical calculations using only the human brain, with no help from any supplies (such as pencil and paper) or devices such as a calculator. People may use mental ca
Rule of 72
In finance, the rule of 72, the rule of 70 and the rule of 69.3 are methods for estimating an investment's doubling time. The rule number (e.g., 72) is divided by the interest percentage per period (u
Mental abacus
The abacus system of mental calculation is a system where users mentally visualize an abacus to carry out arithmetical calculations. No physical abacus is used; only the answers are written down. Calc
Vedic Mathematics
Vedic Mathematics is a book written by the Indian monk Bharati Krishna Tirtha, and first published in 1965. It contains a list of mathematical techniques, which were claimed to have been retrieved fro