Mythical number

A mythical number is a number used and accepted as deriving from scientific investigation and/or careful selection, but whose origin is unknown and whose basis is unsubstantiated. An example is the number 48 billion, which has often been accepted as the number of dollars per year of identity theft. This number "has appeared in hundreds of news stories, including a New York Times piece" despite the fact that it has been shown repeatedly to be highly inaccurate. The term was coined in 1971 by Max Singer, one of the founders of the Hudson Institute.

The origins of such numbers are akin to those of urban legends and may include (among others):
 * misinterpretation of examples
 * extrapolation from apparently similar fields
 * especially successful pranks
 * comical results
 * guess-estimates by public officials
 * deliberate misinformation