|
|
|
zeptogram or zeptogramme is equal to 10-21 gram (unit of mass), comes from a combination of the metric prefix zepto (z) with the gram (g). Plural name is zeptograms.
A grain is a unit of measurement of mass, and, for the troy grain, equal to exactly 64.79891 milligrams. It is nominally based upon the mass of a single seed of a cereal.