What Happened on February 23rd
Derrick Lehmer, one of the world's best known prime number theorists, is born in Berkeley, California. Before World War II, Lehmer invented a number of electromechanical sieves for finding prime numbers and made many important contributions in prime number theory throughout his life. Prime numbers are of interest in themselves as mathematical curiosities but are also of great importance to cryptography. The Computer History Museum has three Lehmer sieves in its permanent collection. Lehmer died in 1991.