Sourced

• Cuius rei demonstrationem mirabilem sane detexi hanc marginis exiguitas non caperet.
  • I have discovered a truly remarkable proof of this theorem which this margin is too small to contain.
  • Note written on the margins of his copy of Claude-Gaspar Bachet's translation of the famous Arithmetica of Diophantus, this was taken as an indication of what became known as Fermat's last theorem, a correct proof for which would be found only 357 years later; as quoted in Number Theory in Science and Communication (1997) by Manfred Robert Schroeder

• • Also known as Fermat's little theorem, the formula above is true for any prime where .