|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
The cubit is an ancient unit based on the forearm length from the tip of the middle finger to the bottom of the elbow. Cubits of various lengths were employed in many parts of the world in antiquity, during the Middle Ages and as recently as Early Modern Times. The term is still used in hedge laying, the length of the forearm being frequently used to determine the interval between stakes placed within the hedge.
The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in onesecond, and is equal to exactly 299792458 metres (just over 186282 miles).