|≈||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 Mark (from Middle High German: Marc, march, brand) is originally a medieval weight or mass unit, which supplanted the pound weight as a precious metals and coinage weight from the 11th century.