Mr. Longbeard, the theoretical answer to your question is the 1.5" low at 25 yards if the spacing between the center of the scope and the center of the barrel is 2". This is calculated by dividing the 2" by 4 which tells you how much the bullet must rise each 25 yards. At 25 yards the bullet has made up the 1/2" of the 2" and thus would still be low 1.5". Keep in mind that this is purely theoretical and does not account for any drop in the bullet which will occur even at 100 yards.

When zeroing a rifle, I normally start at 25 yards and make initial adjustment to get me 1-1.5" low. This should get you between zero and a couple inches high when you move the target to 100.