Magic 8 ball

Ask a yes-or-no question and one of twenty answers comes back. Ten are affirmative, five are non-committal and five are negative — the same distribution moulded into the icosahedral die inside the original toy.

The toy has been made since 1950 and the twenty answers have barely changed. The split is the interesting part: half positive, a quarter negative and a quarter refusing to answer, which is exactly the mix that keeps someone shaking it. Here each of the twenty is equally likely, drawn from your browser’s cryptographic generator, so ten of the twenty faces are affirmative and the odds of a yes-ish answer are precisely half. It goes without saying, but the ball does not know anything — if you find yourself asking twice, you already have a preference and it is worth noticing what it is.