I decided to make a quick project to the Collatz Conjecture: a currently unsolved math law. It goes like this: choose a random number. If it's even, divide it by 2. It it's odd, multiply it by 3 and add 1. Do the same with your result, and keep going. The law is that eventually you will reach 1. This is the project. Enter a random number, and see that eventually the result will be 1.
I'm impressed by how quick this is. Huge numbers can be calculated in seconds. I could even create a private project that sees if I can prove or disprove this (that's probably hoping too high though).