HOW IT WORKS: Forever: If the number is odd, multiply by 3 and add 1 If the number is even, divide by 2 Eventually every number will end up as 1 and will then be multiplied by 3 to make 3. Then if you add 1, it will be 4. 4 divided by 2 is 2. 2 divided by 2 is 1. 1 x 3 + 1 = 4. 4 divided by 2 is 2. 2 divided by 2 is 1. 1 x 3 + 1 = 4 and so on.