If you are trying to sight in at those yardages, and you want to be exact then either get a long tape measurer and have at it or buy a range finder.It's what I did for many years before I boughtmy range finder. Justlay out the tape from where you will be standing and mark the yardage you want to set yout pins at with something. When they are marked start with the closest and work you way out.

Good luck and shoot straight!