A Missouri farmer passed away and left 17
mules to his three sons. The instructions left in the
will said that the oldest boy was to get one-half, the
second oldest one-third, and the youngest
one-ninth. The three sons, recognizing the
difficulty of dividing 17 mules into these fractions,
began to argue.

 Their uncle heard about the argument, hitched
up his mule and drove out to settle the matter. He
added his mule to the 17, making 18. The oldest
therefore got one-half, or nine, the second oldest
got one-third, or six, and the youngest son got
one-ninth, or two. Adding up 9, 6 and 2 equals 17.
The uncle, having settled the argument, hitched up
his mule and drove home.