An introduction presentation-wise for the Fred Kaps $11 Bill Trick: First, recite the old story, with the restaurant and the 3 guests. The bill for the 3 guests is $30. Each pays $10. Later, in the kitchen, the owner states that the bill is actually only $25 and not $30. A mistake happened. So the chef gives 5 single dollar bills to the waiter to give them back to the guests.
But the waiter is dishonest and puts 2 dollar bills into his pocket. He gives back $1 to each guest. So each guest has paid in fact only $9. That makes $27. Plus the two dollars the waiter stole = $29. WHERE is the one dollar? Did it vanish?
After that, perform the Fred Kaps $11 Bill Trick as described in the original manuscript by Anthony Brahams.