Why Mod 3 + Mod 4 Solve This USAJMO Problem (2011 P1)

My thoughts and my solution to the 2011 USAJMO Problem 1. This is my third USAJMO solution, so please let me know if I did anything wrong! "Like" if you want to see my formal write-up, and subscribe for more math resources! The USAJMO is one of the most prestigious and difficult mathematics olympiads in the US; it is part of the American Mathematics Competitions run by the Mathematical Association of America I realized I made a whole discussion about why n must be positive, and I didn't realize that it was in the question! #USAJMO #USAMO #Competition Math