Question about Stephen King's "On Writing" quote?

Question

Does anybody..happen to know around where this formula came from in his book "on writing"?

Edit ruthlessly-take out unnecessary words, especially adverbs and remember this magic formula: 2nd draft=1st draft-10%

Answer 1

He just means that you when writing something, whether it be a novel or short story, don't hold back on your writing. Your "first draft" should be written without hesitation, no editing your ideas--just writing them all down. The "second draft" is your final draft. Now we all know that editing is essential to development of anything. What belongs and what doesn't? Can I put this here instead of this? During the editing stage you should take out a good "10%" of your work. It is very necessary for the "second draft's" final look.

Thus, "2nd draft" is your first draft after editing out 10%.

Answer 2

he's saying the second draft will have less words because you should be removing most adverbs

or did you mean what page is the "formula" found on?

Answer 3

It's sometime after section 10 in the Toolbox, should be before section 13.  I could find the exact quote.  I'm drunk. That's my excuse.  Anyway I narrowed it down for you.