How does 20 questions work? Twenty is not an arbitrary number
Twenty questions. Yes or no answers only. Somebody thinks of a thing, and you have to find it. The number twenty looks like a folk choice, the sort of round figure a Victorian parlour settles on. It is not. Twenty is very close to exactly the right number, and you can derive it. Every question is worth one bit, at best A yes-or-no answer can carry at most one bit of information. One bit halves the space of possibilities. Ask a perfect question and whatever the answer, you throw away half the world. ...