You will need someone to be an accomplice in this trick. Arrange eight cards in the pattern of the symbols on the face of an eight. One of the eight cards must be an eight. While you look away, have a spectator choose a card. When you look back, have your accomplice point to a few cards, saying "was it this one?". Make sure they point to the eight, and to the symbol marking the position of the card the spectator chose. You will get it right every time.
This trick is much more effective after perplexing the spectator by doing the trick several times. The average person will think it is something the accomplice is SAYING, so they probably won't figure out the trick for a while.