|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
The acre-foot is a unit of volume commonly used in the United States in reference to large-scale water resources, such as reservoirs, aqueducts, canals, sewer flow capacity, irrigation water, and river flows.
The attoliter or attolitre is a common metric unit of volume. It is equal to 10-21 cubic meters. Plural name is attoliters.