The Collatz Conjecture is a famously unsolvable math problem, where you take a number and if it's an odd number, you triple it and add one, and if it's even, you halve it. The conjecture says that all numbers will eventually reach 1, (and then get stuck in the 4, 2, 1 loop) but there's no way to prove it. Test the conjecture for yourself by inputting a whole number and watching!
It now calculates as fast as possible so you can put in large numbers and not wait 6 hours. This took several seconds to make.