ERATOSTHENES, SIEVE OF

systematic procedure for finding prime numbers (numbers not divisible by an integer greater than one, except themselves) with all the natural numbers arranged in order. After striking out the number 1, one simply strikes out every second number following the number 2, every third number following the number 3, and continues in this manner to strike out every nth number following the number n. The remaining numbers, from 2 on, will be prime numbers. The procedure is named for the 3rd-century-BC Greek astronomer-mathematician Eratosthenes of Cyrene.