Hi guys , I'm mentalist and I'm really confused I want to know how this trick done ! 6 bags one of them containing a nail and the other are empty ,, then the magician asks the spectator to decide what they want he slams his hand over the chosen one , the bag is empty! And continues over that finally the last one containing a nail ( the other bags which empty are not containing a nail) how it's done please .. Second 4 different bills are shown then the mentalist put a prediction paper in front of participant before doing anything then the mentalist tolds him while he turned back to pick a bill and put it at any 4 different packet then the second , third and last same way finally the prediction matched ( for ex. : 5$ in front right , 10$ in back left .. etc) please help me thank you