When a vitamin or supplement claims, for example, that it contains
600 mg of calcium (as calcium carbonate)
what does that mean? Does each tablet contain 600 milligrams of the element calcium?
Or does a tablet contain 600 milligrams of the compound calcium carbonate? In that case, using the molar masses of Ca and CaCO3, each tablet would contain only
600 * (40.1 / 100.1) = 240.4 milligrams of the element calcium.