All you do is answer the question. Go do something else for a bit, and come back. Even if someone else used it, you should have the same number.
This is an attempt to make a system that saves values to a username. For the numbers, it just converts the numbers into a larger decodable number. For the usernames, it turns the number that saves into a list of codes, then those codes into the actual users. Whem the decoding half worked, I was happy.