Help me to work out this math problem For a non-zero natural number, the operation is as follows: if it is even, divide it by two; if it is odd, add 1. The operation does not stop until the number is 1. How many numbers have changed to 1 after 9? Also, I'm in a hurry. I'll be in a hurry in 10 minutes

Help me to work out this math problem For a non-zero natural number, the operation is as follows: if it is even, divide it by two; if it is odd, add 1. The operation does not stop until the number is 1. How many numbers have changed to 1 after 9? Also, I'm in a hurry. I'll be in a hurry in 10 minutes

It's 17