The performer takes out 9 chips and a key holder from a box. The chips are numbered from 1 to 9 representing the different room numbers.
One of the spectators chooses one from the numbered chips. The number on the chosen chip perfectly matches the room number on the key holder.
The experiment can be performed to a married couple too. In this case both of them will choose the same numbered chip.
Of course the chosen number will perfectly match the room number on the key holder.
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* applies to deliveries within Germany, delivery times for other countries can be found on the shipping information button