Mental Jackpot, Poker Size by Astor

Four transparent envelopes, one of which contains a banknote, and each of the other three has only a small white piece of paper inside. Three spectators choose three of the four envelopes. All three contain white papers while the remaining envelope (left for you) contains the banknote. The routine is surprising and clear, performance is very simple, and does not require any sleight of hand.