Why 4 Horcruxes left, and not 3??

[a_svirn]

No: HPFGUIDX 142098


> Christina:
<snip> 
> For simplicity's sake, let's just
> say that the only murders Voldemort commits are used for
> horcrux-making.  That means his first horcrux would have 1/2 of his
> original soul in it, and Voldemort would retain 1/2 of his original
> soul.  For the second horcrux, Voldemort would split the amount of
> soul he currently has in two again, meaning that his second horcrux
> would have 1/4 of the *original* soul and Voldemort would have 1/4 
of
> his *original* soul.  For horcrux #3, Voldemort's 1/4 of a soul 
splits
> in half again, so the horcrux and Voldemort each have 1/8 of the
> original soul.  And so on and so forth.  

This you must ken!
From one make ten,
And two let be,
Make even three,
Then rich you'll be.
Skip o'er the four!
>From five and six,
The Witch's tricks,
Make seven and eight,
'Tis finished straight;
And nine is one,
And ten is none,
That is the witch's one-time-one!

Faust by Johann Wolfgang von Goethe