Don't remember where I picked this up, but it was years ago, probably in grade school.
While traveling there were three guys who needed to stay in a hotel overnight. Upon checking in the manager told them the cost would be $30.00 for the night. So each man took ten dollars out of his wallet and paid the manager his share.
A bit later the manager realized that he had overcharged the men for their room. It should have only cost $25.00. So, being the honest man that he was he called the bellhop over and explained his error. He gave him five dollars and asked that he return it to the men.
Now the bellhop, being clever but not necessarily honest, realized there would be no way for the men to equally divide the five dollars three ways. Figuring no one would be the wiser he decided to give each man back one dollar and pocket the other two for himself.
So that's just what he did and everyone was satisfied. The manager had done the honorable thing, the men were happy to get a refund and the bellhop made an easy two bucks for his effort.
It all sounds good and well until you do the math. Each man originally paid ten dollars apiece for a total of $30. They each received one dollar back so in essence they paid nine dollars each. The bellhop kept two dollars for himself. Make sense so far? Let's add it up now.
3 men paid $9 each for a total of $27 plus the $2 for the bellhop.
$27 + $2 = $29
Where did the other dollar go?