Number Puzzle!!

I have figured out this number puzzle thing, and it really works!

Right here goes.

1. Think of ANY positive number e.g 47. With no decimal places.
2. Double it.
3. Add 6.
4. Divide it by 2
5. Then take away the number you first thought of...
6. And the answer is..... 3!!

If it isn't you've gone wrong! :) Trust me...:)

P.S If you know how this works, please don't ruin the fun :)