This is an old question but it can still be fun for those who haven't heard it or solved it. If you know the answer please give a like :) If you are seeing for the first time then please give your reasoning :)

Three people check into a hotel.

They pay $30 to the manager and go to their room.

The manager suddenly remembers that the room rate is $25 and gives $5 to the bellboy to return to the people.

On the way to the room the bellboy reasons that $5 would be difficult to share among three people so he pockets $2 and gives $1 to each person.

Now each person paid $10 and got back $1.

So they paid $9 each, totalling $27. The bellboy has $2, totalling $29.

Where is the missing $1?