Reasoning

Decoding the Cards

Difficulty
You and your partner are presented with a challenge using a standard deck of cards. Five cards will be drawn randomly from the deck. Your task is to devise a system where you can hand over four of these five cards to your partner. Using only the information conveyed through these four cards, your partner must be able to name the fifth (hidden) card exactly, stating both its rank and its suit. Is there a method that guarantees success every time? If so, explain how it works.
Reported at 3 firmsJane Street · J.P. Morgan · IMC TradingI’ve seen this in an interviewI’ve seen this
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