Many years ago, I worked a second job as night clerk at the Coronet motel on rt.1 in peabody ma. when three men came in looking for a room to crash after driving all day and night. I charged them thirty bucks, they each gave me a ten and I then escorted them to their room. Early the next morning my boss came in and noticed that the three guys checked in after midnight and I should have charged them twenty five dollars not thirty. He gave me their change and told me to bring it to them. On the way to their room I decided to keep two bucks for myself for carrying their bags. I knocked on their door and when they answered I explained to them that I over charged them and owed them each a dollar. So here is the problem, originally they each paid 10 dollars, 9 x 3 = $30.00. Now they each paid 9 dollars, 9 x 3 = $27.00. I kept $2.00, 27 + 2 = 29, where is the missing dollar?