Missing Dollar

Three traveling companions arrived late one night at a hotel. 

“There’s only one room left” said the clerk, “and it’s 30 dollars”

So they each pitched in 10 dollars for the 30 dollar room.

The next morning the general manager noticed that the night clerk had charged the men 30 dollars for a 25 dollar room so he gave the bellhop the 5 dollar overcharge and told him to return it to them.

The bellhop, being dishonest, pocketed 2 dollars and returned one dollar to each of the men, telling them that their individual charge was only 9 dollars each for the room.

Adding together the 9 dollars that each of the 3 men paid gives you 27 dollars;
Plus the 2 dollars the bellhop took ads up to 29 dollars.

Where is the remaining dollar?