Final answer:
The numbers in ellipsoid and datum names like 'NAD27' and 'WGS84' refer to the year they were established or revised, playing a role in cartography, navigation, and geodesy for location description.
Step-by-step explanation:
The numbers in the names of ellipsoids and datums such as the "27" in NAD27 and the "84" in WGS84 typically refer to the year that the ellipsoid or datum was defined or last revised. In the given examples, NAD27 refers to the North American Datum of 1927, and WGS84 refers to the World Geodetic System of 1984. These systems are part of a set of coordinates used in cartography, navigation, and geodesy for accurately describing locations on the Earth's surface or in space.