We did Fermat’s Little Theorem today in Problem-Solving, and I didn’t realize that this Wikipedia article was out there. It contains five (count ’em!) different proofs of this important number theory result. It’s always instructive to see the same result proven in multiple ways — this is the essence of Polya stage four — especially so when you have more than three proofs from more than three different directions. One of the proofs even utilizes dynamical systems, which is an approach I’d never seen before but which is cool and makes a lot of sense.