Numbered Headings in Org-Mode, Emacs

Orgmode now has a built-in minor mode for this, contributed by Nicolas Goaziou.

Simply do M-x org-num-mode to activate the display of dynamic headline numbering.

If you are looking for a way to show this in Org itself, then I'm afraid this is not possible. However you can do this easily in the exported document. Look at the exporting chapter in the manual.

You can provide an option like this: #+options: num: 2. Then all headlines at the 2nd level or above will be exported with a number. You could then adjust the headlines as you wish in Org, without affecting the numbers in the exported document.