What a mathematic

A person was about to die, and before dying he wrote his Will which
went as follows ...
"I have 17 Camels, and I have three sons. Divide my Camels in such a
way,that My eldest son gets half of them, the second one gets 1/3rd of
the total and my youngest son gets 1/9th of the total number of Camels"
After his death when the relatives read his will they got extremely
perplexed and said to each other that how can we divide 17 camels
like
this.
So after a long hard thought they decided that there was only one man
in
Arabia who could help them: "Ali Ibne Abi Taalib."
So they all came to the door of Ali (RATA) and put forward their
problem.
Ali (RATA) said, "Ok. I will divide the camels as per the man's
will."
Ali (RATA) said, "I will lend one of my camels to the total which
makes
it
18 (17+1), now lets divide as per his will"
The Eldest gets 1/2 of 18 = 9
The second one gets 1/3 of 18 = 6
and The Youngest gets 1/9 of 18 = 2
Now the total number of camels = 17
Then Ali (RATA) said, "Now I will take my Camel back"