how do apps like the original 20 questions game work?

Question

i downloaded an app that’s similar to the handheld 20 questions game i had as a kid.

i’m thinking of the most obscure characters and it still guesses it every time. someone please explain to me how this works

In: Technology

Answer 1

If you can ask a question that divides the number of possibilities in half, then from 20 questions you can narrow it down from a list of a million possible characters.

Take a million and cut it in half 20 times, you end up with about 1 left.