Why can some fortune tellers tell your last name accurately?

This is very simple. For example, there are three rows of numbers: the first row is 123, the second row is 456 and the third row is 789. For example, your favorite number is "2" in the first row (of course, the other party doesn't know). Then separate the first line (the one that likes numbers), such as 145 289 367, so that if you choose numbers again,