Re: Newb question (long post)
You state that your scope is 1/8 "clicks".
If you zero your rifle (rifle,ammo,scope setup) at 100 yards you should print a group zero inches high, zero inches low and with correct windage.
Now, if you "click" your scope up 8 click and shoot again at 100 yards you should be approx. 1" high (point of impact 1" above point of aim).
If you have your scope set to your 100 yard zero (point of aim = point of impact at 100 yards) and shoot a group at 200 yards your group will be below your point of aim by several inches. Walk to the 200 yard target (imaginary so we can do this quickly) and measure the distance the group is below the point of aim. We'll call it 2.25 inches low....
Your question is how much do you need to adjsut the scope to make the 200 yard group match the point of aim at 200 yards.
The imaginary group we just shot (low recoil group) is 2.25 inches low. To move that group to match point of aim we need to adjust the elevation an amount equal to 2.25" at 200 yards... The value you need to accomplish this is determined by dividing the distance to move the point of impact by the distance in hundreds of yards. 2.25" / 2 (2 hundred yards) = 1.125 (MOA in reality) You need to adjust your scope 9 "clicks" up to make the 1.125 MOA. This adjustment will make 2.25" at 200 yards.
We'll shoot another imaginary group....
High speed walk and measure and it's 20" low using the 100 yard zero.
To calculate the adjustment needed, 20" / 4 (400 yards) = 5 MOA (not exact but close enough for us) of correction required. You have a 1/8 MOA scope so we need to come-up 5 MOA or 5 X 8 = 40 "clicks" for a 400 yard zero.