A deck of 52 cards is given. There are four suites each having cards numbered 1, 2, ...., 13. The audience chooses some five cards with distinct numbers written on them. The assistant of the magician comes by, looks at the five cards and turns exactly one of them face down and arranges all five cards in some order. Then the magician enters and with an argument made beforehand with the assistant, he has to determine the face down card(both suite and number). Explain how the trick can be completed.