(n.) According to the French notation, which is followed also upon the Continent and in the United States, a unit with fifteen ciphers annexed; according to the English notation, the number produced by involving a million to the fourth power or the number represented by a unit with twenty-four ciphers annexed. See the Note under Numeration.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). quadrillion. Retrieved September 26, 2026, from http://smartdefine.org/quadrillion/definitions/2051570 |
| Chicago | Webster's. 2011. "quadrillion" http://smartdefine.org/quadrillion/definitions/2051570 (accessed September 26, 2026). |
| Harvard | Webster's 2011, quadrillion, Smart Define, viewed 26 September, 2026, <http://smartdefine.org/quadrillion/definitions/2051570>. |
| MLA | Webster's. "quadrillion" 27 May 2011. Web. 26 September 2026. <http://smartdefine.org/quadrillion/definitions/2051570> |