# Mprime (Cray)

**mprime** was the software, initially authored by David Slowinski (later versions with Paul Gage), for testing Mersenne numbers for primality on Cray supercomputers.

This software is responsible for the discovery of 7 Mersenne primes. It used Fast Fourier transforms for the multiplication of very large numbers. This represented an advance over the software used by Landon Curt Noll & Laura A. Nickel. Noll had suggested the use of FFT's, but had not implemented them until after his discovery of M26.