The works of the 17th-century mathematician Pierre de Fermat engendered many theorems. Fermat's theorem may refer to one of the following theorems:
- Fermat's Last Theorem, about integer solutions to a<sup>n</sup> + b<sup>n</sup> = c<sup>n</sup>
- Fermat's little theorem, a property of prime numbers
- Fermat's theorem on sums of two squares, about primes expressible as a sum of squares
- Fermat's theorem (stationary points), about local maxima and minima of differentiable functions
- Fermat's principle, about the path taken by a ray of light
- Fermat polygonal number theorem, about expressing integers as a sum of polygonal numbers
- Fermat's right triangle theorem, about squares not being expressible as the difference of two fourth powers
See also
- List of things named after Pierre de Fermat