A man has a will in which he divides his property. Among his assets are the mans beloved horses which are his most prized and trusted friends. This man has three sons in varying favor. This is what he wrote in his will. “… To my eldest I give one half of my horses. To the middle son I give one third of my horses. To the youngest and least favorite I give one ninth of the horses. The horses are to be divided exactly as specified. The horses are not to be sold under any circumstances. There can be no agreements or arrangements made between my sons, each has to receive his fair share.”

There were only seventeen horses to the mans property, how to divide them according to the will?

The answer is : 9, 6, 2.

First of all, the man “borrows” one horse from a neigbour, then the total horses become 18, then

18 X 1/2=9

18 X 1/3=6

18 X 1/9=2

Finally he gives the horses (9+6+2=17) to the sons, and then he “returns” one horse back to his neigbour.

How tf are we supposed to know he borrowed a horse?