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See also: sagan and saĝan


Alternative forms[edit]


The unit is derived from the phrase billions and billions (of stars), frequently attributed to the American astronomer Carl Sagan. The lower bound of a number must be two billion plus two billion, or four billion. Johnny Carson popularized the phrase through his occasional impersonation of Sagan throughout his career.


Sagan (plural Sagans)

  1. (slang, humorous) A unit of measurement equal to at least four billion.


  • Sagan at (Jargon File)
  • William Safire, ON LANGUAGE; Footprints on the Infobahn, New York Times, April 17, 1994
  • Carl Sagan, Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium, Random House, 1997