Fermat's Theorem(redirected from Fermat theorem)
Fermat's theorem[′fer‚mäz ‚thir·əm]
(or Fermat’s lesser theorem), a fundamental theorem of number theory. The theorem states that if p is a prime number and a is a whole number not divisible by p, then ap–1 – 1 is divisible by p—that is, ap–1 ≡ 1 (mod p). The theorem was set forth by P. Fermat without proof; the first proof was given by L. Euler.