There are well over 371 Pythagorean Theorem proofs, originally collected and put into a book in 1927, which includes those by a 12-year-old Einstein (who uses the theorem two decades later for something about relativity), Leonardo da Vinci and President of the United States James A. Garfield.
Elisha Scott Loomis, an eccentric mathematics teacher from Ohio, spent a lifetime collecting all known proofs of the Pythagorean Theorem and writing them up in The Pythagorean Proposition, a compendium of 371 proofs. The manuscript was prepared in 1907 and published in 1927. A revised second edition appeared in 1940, and this was reprinted by the National Council of Teachers of Mathematics in 1968 as part of its‘ Classics in Mathematics Education’ series. Loomis received literally hundreds of new proofs from after his book was released up until his death, but he could not keep up with his compendium. As for the exact number of proofs, no one is sure how many there are.
- Pythagoras: Everyone knows his famous theorem, but not who discovered it 1000 years before him
- the sense that it reveals the connection between length and area that is at the heart of the theorem. (Albert Einstein)
- Euclid I 47 is often called the Pythagorean Theorem, called so by Proclus.
- Garfield’s aptitude for mathematics extended to a notable proof of the Pythagorean theorem, which he published in 1876.