|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
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.
Femtogram or femtogramme is equal to 10-15 gram (unit of mass), comes from a combination of the metric prefix femto (f) with the gram (g). Plural name is femtograms.