In La Bibliothèque de Babel (The Library of Babel), a short story by the Argentine writer Jorge Luis Borges first published in French in 1951 in the collection Fictions (Gallimard), Borges describes a gigantic library containing every book written since the dawn of humanity. Well, almost…
Jorge Francisco Isidoro Luis Borges Acevedo (1899–1986).
Similarly, a universal number (in base 10) is a real number whose decimal expansion contains, after the decimal point, every possible finite string of digits. The concept extends to every base.
The term "universal number" seems to have been introduced by Jean-Paul Delahaye, well known to readers of Tangente, in his article Les Nombres Univers (Pour la Science 225, July 1996); English-language literature tends instead to use the terms rich number or disjunctive number.
