Three people check into a hotel.
They pay \$30 to the manager and go to their room.
The manager suddenly remembers that the room rate is \$25 and gives \$5 to the bellboy to return to the people.
On the way to the room the bellboy reasons that \$5 would be difficult to share among three people so he pockets \$2 and gives \$1 to each person.
Now each person paid \$10 and got back \$1.
So they paid \$9 each, totalling \$27.
The bellboy has \$2, totalling \$29.
Where is the missing \$1?