I got a math problem for you:

3 guys go into a motel.
The clerk says $30.
Each man pays $10.
The manager comes in later and says $30 was too much give them back $5.
The clerk thinks 5 doesn't divide by 3, so he puts two in his pocket, gives each guy $1.
So, each fella paid $9.
Times 3 is $27.
$2 for the clerk makes $29.
Where is that missing dollar?