I ran across this thing over a year ago, and finally gave up on it. Mull it over a while. What's the deal?

[b]Three guys ordered a couple pizzas for $30. The delivery boy brought the pizzas, and the three guys each gave him a $10 bill.

The pizza boy went away disappointed that he didn't get a tip. He took the $30 back to the manager.

However, the manager said that there was a mistake and the pizzas were only supposed to cost $25, so he gave the delivery boy five $1 bills to return to the customers.

On the way, the boy remembered that these three guys didn't give him a tip. Since he couldn't split five dollars three ways evenly anyway, he kept two dollars for himself and gave each of the three guys a dollar back.

Do you follow this so far? Everything is fine, right?

Consider this:

Each guy paid a 10 dollar bill for the pizzas, and got back a dollar in change. That means they each paid 9 dollars for the pizzas.

$10-$1=$9

The price of the pizza was 3 times $9, or $27.

3 x $9 = $27

The pizza delivery boy collected a $2 tip. This brings the total cost of the pizzas, including the tip, to $29.

$27 + $2 = $29

But the guys paid $30 for the pizzas. $30

So, who ended up with the other dollar?

Can you explain what went wrong? It could happen to you![/b]