(defun my-number-region (beg end)
  (interactive "r")
  (save-excursion
    (let ((end (progn (goto-char end) (beginning-of-line 2) (point-marker))))
      (goto-char beg)
      (beginning-of-line)
      (loop for i = 1 then (1+ i)
	 while (< (point) (marker-position end))
	 do (progn
	      (insert (format "%-6d" i))
	      (beginning-of-line 2))))))