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For the modem manufacturer, see Billion (company).

The word "billion" and its equivalents in other languages refer to one of two different numbers.



The original meaning, established in the 15th century, was "a million of a million" (1,000,0002, hence the name billion), or 1012 = 1 000 000 000 000. This system, known in French as the échelle longue ("long scale"), was formerly used in the United Kingdom and is used in most countries where English is not the primary language. 1012 is referred to as a trillion in the "short scale" system.


In the late 17th century a change was made in the way of writing large numbers. Numbers had been separated into groups of six digits, but at this time the modern grouping of three digits came into use. As a result, a minority of Italian and French scientists began using the word "billion" to mean 109 (one thousand million, or 1 000 000 000), and correspondingly redefined trillion and higher numbers to mean powers of one thousand rather than one million. This is known in French as the échelle courte ("short scale") and is now officially used by English-speaking countries, as well as Brazil, Puerto Rico, Turkey, Greece and the Netherlands.


Use of "thousand million" for 109 and "million million" for 1012 can avoid ambiguity; however, British media, including the BBC, which long used "thousand million" for this reason, generally use "billion". The old word "milliard", also found in many other languages, can be used for 109 but is unfamiliar even to many native English speakers. See long and short scales for a more detailed discussion and usage advice.


The facts below give a sense of how large one billion (taken as 109) is in the context of passage of time.

  • About a billion seconds ago, the parents of middle school children were themselves in elementary school. (One billion seconds is roughly 31.7 years.)
  • About a billion minutes ago, the Roman Empire was flourishing. (One billion minutes is roughly 1,900 years.)
  • About a billion days ago, Australopithecus, an ape-like creature thought to be an ancestor of modern humans, roamed the African savannas. (One billion days is roughly 2.7 million years.)
  • About a billion months ago, dinosaurs walked the earth during the late Cretaceous. (One billion months is roughly 82 million years.)

In terms of distance:

  • A billion inches is 15,783 miles, more than halfway around the world and sufficient to reach any point on the globe from any other point.
  • A billion meters is almost three times the distance from the Earth to the Moon.

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