Where's the $1?

I am reading really quickly thru' this particular book when i came across this short story... maybe someone can solve the "mystery"? haahaa
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It was a dark and stormy night. Seeking refuge from a worsening storm, three men - strangers to each other - race into a small hotel at the same time. The clerk tells the three men that only 1 room is left. A $30 room. The men agreed to share the room. Each man hands the clerk $10.

Minutes after going into the room, there's a knock on the door. It's a bellboy who says, "The desk clerk made a terrible mistake. The room is only $25." The bellboy then placed five $1 bills on a table.

Each man picked up a dollar. The remaining $2 was given to the bellboy as a tip.

The next day, one of the men told the story to his wife. "I originally paid $10, but I got back $1. So I paid $9 and contributed one-third of the $2 tip," he said.

"Wait a minute," she said. "three times the $9 you each paid is $27. And the $2 tip the bellboy got makes it a total $29. What happened to the other $1?"
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took me a couple of minutes to realise what was wrong. what a shame as a math major. tsk.