|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
attogram or attogramme is equal to 10-18 gram (unit of mass), comes from a combination of the metric prefix atto (a) with the gram (g). Plural name is attograms.
The unified atomic mass unit or dalton (symbol: u, or Da) is a standard unit of mass that quantifies mass on an atomic or molecular scale (atomic mass).