ok based on what texasck1 says, if you have a no# 14.77 inches. just measure down 14 3/4 of an inch. based on that .25 would be 1/4 inch, .50 1/2 inch .75 3/4 inch. right?? ok at first i figured that would be fine,but when a no# comes up like 12.21 or 13.52, what do you do round it off to the nearest no#?? that dose not seam at all very percise, and what started this hole thing was ,i whent to one of the cp, libareys, and i figured i would see if could work the math out to find the cp of any rocket. first problem was that every rocket listed had at least 2 diferent measurements for any given rocket, and even from the same programe, rocsim, winroc, and outhers. how could this be?? I thout to my self ., so i grabed one of my rockets.opened winroc. and started to measure. to see if i could come close to any body elses answer for that particular rocket. I used estes, chrom dome. well when i got done, there was a inch diference. between mine and there's. now are you following so far?? if you are rounding off this numbers say, .22 is .25 witch would be 1/4 of an inch. by the time your done you could be 1 to 2 inches longer or shorter then you should be. right or wrong?? and every body wrights there fig. like that. it has to be more percise then that. thanks