1.9, due on September 21

This was an incredibly interesting chapter! Refreshing familiar rules of modular arithmetic was nice, but going over some of the more obscure (and practical) rules, such as fast exponentiation, finding inverses, etc was really neat. I also really the "Freshman's Dream" corollary; the naming was pretty great, and will likely make it easier to remember.

I was a little intimidated by Fermat's Little Theorem, however. The notation combining combinatorics and modular arithmetic is going to take some getting used to. I felt like C(p,k) came out of left field, and I'm having a hard time understanding the reason for it.