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. 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
Examples of Mythical Numbers
* The claim that humans use only 10% of our brains
* The five-second rule, regarding the eating of dropped food
* The recommendation to chew food exactly 29 times before swallowing
* Singer, Max (Spring 1971). "The vitality of mythical numbers". Public Interest (23): 3–9. Online at edwardtufte.com.
* Reuter, Peter (1987). "The (continued) vitality of mythical numbers". Public Interest (75): 79–95.
* Cook, Philip J.; Jens Ludwig, David Hemenway (Summer 1997). "The gun debate's new mythical number: how many defensive uses per year?". Journal of Policy Analysis and Management 16 (3, special issue: The New Public Management in New Zealand and beyond): 463–469.