three men go to a hotel and book one room, The cost is $30 a night. The men split the cost, $10 a piece.
The hotel manager sees that he overcharged them, the room only cost $25 a night.
The manager sends the hotel clerk to the room with $5 to refund to the three men. He can't figure out how to evenly split it so he gives each one $1 back and keeps $2 for himself.
Now the three men only paid $9 apiece for the room equaling $27.
The clerk kept $2, that equals $29.
Question: What happened to the extra dollar?