The next day, a man with a suit and briefcase riding a camel comes to the sheik's sons. They explain the arithmetical conundrum. "No problem at all," says the consultant, "Take my camel."
Now with 18 camels, the sums make sense. One-half of the camels, nine, go to the eldest son; one-third, or six, to the middle son; and one-ninth, two camels to the youngest.. But wait... nine plus six plus two makes only 17 camels. What about the 18th?
"That one's mine." says the consultant, and rides away.