Three weary travelers arrive at a hotel in Edmonton, and each pays $10 to the hotel owner for a one-night stay.

Q: How much did the guests pay in total?
A: 3 * $10 = $30

After the men had left the office, the owner thought to himself that he had charged them too much, so he called the porter into his office.

"I've overcharged the three men too much - here's $5. I want you to take it to them and give them a refund on their rooms."

The porter thought to himself that it would be difficult to split the $5 between the three men, so he decided to take a $2 tip for himself, then gave each of the hotel guests a dollar each between the three of them.

Q: With the refund, how much did the guests now pay in total?
A: 3 * $9 = $27

Q: So the total money involved was $27 plus the $2 for the porter tip = $29.
Where's the missing dollar gone?