The Most Famous Document of Babylonian Mathematics: Plimpton 322. Plimpton 322 reveals that the Babylonians discovered a method of finding Pythagorean triples, that is, sets of three whole numbers such that the square of one of them is the sum of the squares of the other two.
Love this Pythagorean theorem maze for my Geometry unit! This would be a perfect lesson / activity for an observation day. 8.7C Use the Pythagorean Theorem and its converse to solve problems. G.9B Apply the relationships in special right triangles and the Pythagorean Theorem, including pythagorean triples, to solve problems.
This is the published (by his son) version of Pierre de Fermat's annotation of Diophantus' Arithmetica. Here Fermat writes that he has a 'a truly marvellous' proof that any Pythagorean Triples when added have no whole number solutions when n>2. This is from which we derive Fermat's Last Theorem.