Where did the $1 go?

3 men booked in a hotel. Counter girl charged them $10 for 1 room each. So total they paid $30.

Manager comes in after the men went to their rooms and reminded the counter girl they are having promotion. 3 rooms for $25.

Counter girl passes $5 to bellboy and told him to return the 3 men. Bellboy thinks $5 cannot divide by 3 so he kept $2 and return each man $1.

So each man paid, $10 - $1 returned by bellboy = $9

3 men = 3 x $9 = $27.

Bellboy kept $2.

$27 + $2 = $29.

Where is the missing $1???

PS: This is one tricky scenario! I almost fell for it.