 And then you do it again. So whatever number pops out, if that number is even, you divide it by two again. If it's odd, you multiply by three and add one. And you continue this process. And if you do it enough times, you'll find that no matter what number you start with, you always end up in a circle that goes 4, 2, 1, 4, 2, 1, 4, 2, 1.