GenailleLucas
Genaille-Lucas is a historical calculating device used to perform long division and multiplication. Developed in the late 19th century by French mathematician Édouard Lucas in collaboration with Henri Genaille, the device consists of a stack of interlocking sliding rulers, each printed with a sequence of digits. When set with a dividend and a divisor, the user reads successive digits off the rulers to obtain the quotient digits.
The rulers are designed so that borrows are handled automatically by precomputed complements, eliminating the need
The Genaille-Lucas devices were popular as teaching aids and novelty calculators in the late 19th and early
Surviving examples are preserved in science museums and private collections, and the devices are discussed in