The question, as stated, cannot be answered sensibly. A cubic centimetre (cc) is a measure of volume, with dimensions [L3]. A milligram is a measure of mass, with dimensions [M]. The two measure different things and elementary dimensional analysis teaches that you cannot convert between measures with different dimensions such as these without additional information.
As a simple mental exercise consider a cc of air and of water. They will have very different masses.
20 cc
1/2 of a cc/ml
20mg = 2cg (10mg per centigram).*Centigrams x 10 = mg*Milligrams/10 = cg
Simply multiply the mg's by the amount of pills. 20mg x 29 pills = 580mg in 29 pills.
That is 5,000 cc
2,750 cc
250
1 gallon = 3785.41 cc
473.176473 cc American568.26125 cc UK
20mg
20mg is approximately 0.0007055 ounces.
3 CC = HOW MANY MG