Password Lock

The performer introduces a combination Padlock. He emphasizes that the lock can not be opened by any random series of numbers. He then asks a volunteer to hand over his/her wedding ring. The performer locks the wedding ring on the lock and spins the wheels to change the numbers. He then gives the lock to the volunteer to try to open the lock by setting any random numbers. Naturally the volunteer fails after several attempts. Finally the magician asks the volunteer to use the year of their marriage as the combination number of the lock. The Lock opens.