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You have four cards. The assistant takes one of the four cards away (the card that follows their tactic). The other cards stay where they are (don’t turn them, move them…). Then the magician comes in and can determine the suit of the fourth card by looking to the remaining three cards (and maybe their Numbers and place where they lie) They can’t move or touch the other cards. How?

Kate Gregory
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Magiciangeek
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  • How much does the magician know of the position of the removed card? (Exact position / second, third, or endpiece / nothing) – ralphmerridew Jan 15 '23 at 21:47
  • I assume the 4 cards are chosen randomly? The way the question is asked, you could always start with the 4 aces. – Florian F Jan 15 '23 at 23:57
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    Option a: Spectator chooses four cards and puts them on the table. Assistant turns one over and leaves. (Magician knows whether cards was leftmost, second, third, or rightmost.)

    Option b: Spectator sets out four equally spaced cards. Assistant removes one and leaves. If it was one of the middle cards, magician sees unequal gaps.

    Option c: Spectator sets out four cards. Assistant removes one. Spectator then puts them equally spaced, keeping the order.

     – ralphmerridew Jan 16 '23 at 03:31
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    You really need to answer clarifications questions about what information the magician knows/can know, or this won't a solvable puzzle, it'll be a guessing game as to which solution you're thinking of – bobble Jan 16 '23 at 05:13

1 Answers1

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Strategy for the assistant

Choose an ordering for the suits, for example 'clubs, diamonds, hearts, spades' so we can compare cards of the same suit by value and cards of different suit by suit (e.g, 10 of clubs is less than 7 of diamonds).

If there are at least two cards of the same suit, remove one of them and put one of the others on the left of the remaining three. Then place the other two cards in order.

If the four cards are all of different suits, remove any one of them. Put any card on the left and then place the other two cards in reverse order.

For the magician

If the second and third card are in order, guess the suit of the first card.
If the second and third card are in reverse order, guess the suit which isn't present.

hexomino
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  • I think this doesn’t work for cases with f.e. three cards of the same suit. It is also not possible to move the cards. – Magiciangeek Jan 15 '23 at 21:25
  • @Magiciangeek By two here, I really mean at least two so the strategy still works. I've edited to clarify. – hexomino Jan 15 '23 at 21:36
  • @Magiciangeek Are you saying the assistant cannot move cards because that is distinctly different from Fitch Cheney where the communication depends on that. – hexomino Jan 15 '23 at 21:37
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    If the magician cannot move the cards, will it be apparent which card was removed? For instance the 4 cards are lying on the table and one gets removed leaving a gap. – Florian F Jan 15 '23 at 23:54
  • The assistant takes one of the four cards away ( the card that follows their tactic). The other cards stay where they are (don’t turn them, move them…). Then the magician comes in and can determine the suit of the fourth card when he looks to the reamaining three cards (and maybe their Numbers and place where they lie). – Magiciangeek Jan 16 '23 at 06:37
  • I think the number on the card is important and that even/odd has something to do with it. – Magiciangeek Jan 16 '23 at 06:41