3 college kids are driving back from Spring Break, and stop at a roadside hotel for the night. They walk up to the front desk and ask what the cheapest room rate is.
"$30", says the manager.
"Hey, that's only $10 bucks each! That's good. We'll take the room."
As the future economists settle into their room, the manager reminisces about his college days. He figures he can cut the kids a better deal, since college kids are always short on cash.
He calls the bellhop (don't ask, its just a riddle) over, and says, "I really only need to charge $25 for the room. Here's five (5) $1 bills...please return this to our collegiate guests."
So, the bellhop takes the money. He isn't sure how to split the $5 amongst the 3 kids, and figures he ought to get something for his troubles, so he pockets $2 and gives the kids back $1 each.
So...instead of $10 each, they got a dollar back each, so they have now paid $9 each. 3 x $9= $27. Plus the Bellhop kept $2...so that's a total of $29. What happened to the extra dollar???