How many mg to cc?

Well, mg (milligrams) is a mass measurement and cc (cubic centimeters) is a volume measurement. If we are talking about pure water and approximating, there are approximately 1000 mg of water (at 4 degrees celsius) in one cc. For other substances, the answer will depend on the density of the substance. Be careful, though. If a substance like water is used as a solvent for something (let's say, compound X), you need to know the concentration of compound X in the solution to determine how many milligrams of X are in 1 cc of the solution. So we really need more information for a reliable answer.