# Conversion of the units BeV (US) and GeV (UN)

What is the difference in the definition of a billion electron volts in United states (US) and United Nations (UN)?

When the US people say billion, do they mean $10^{12}$ or $10^9$?

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Nobody has used BeV in a serious context in decades. –  dmckee Jul 4 '12 at 18:10

In the US, 1 billion = $10^9$.

The difference is between the Long and short scales. The US uses the short scale, where a billion is $10^9$. In the long scale, a billion is $10^{12}$.

In the short scale, every term after a million (billion, trillion, etc.) is 1,000 times bigger than the previous one. So, million = $10^6$, billion = $10^9$, trillion = $10^{12}$.

In the long scale, every term after a million is 1,000,000 times bigger. So, million is again $10^6$, but billion = $10^{12}$, and trillion = $10^{18}$.

If you just use SI prefixes, though, those are the same everywhere. $10^9 eV$ is one GeV, whereas $10^{12} eV$ is one TeV.

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milliard=$10^{9}$ –  Non-standard model Jul 4 '12 at 16:43
@Non-standard: yes, milliard is a term used to describe one thousand millions in the long scale. Where I live, if you said milliard they would look at you as if you were crazy (unless they knew French, in which case they would understand exactly what you meant :) ) –  Ord Jul 4 '12 at 16:51
your's definition is complete but this could be origin of thousands problems when you try to translate a physics lecture!! how can i release what was the goals of authors!? –  Non-standard model Jul 4 '12 at 16:54
@Non-standardmodel Hmmm, that is tricky! The wikipedia article I linked has a list of countries that use each scale, so if you know the nationality of your author, you can make a pretty educated guess. Also, you know that your author is going to consistently use only one system, so if you ever see terms like milliard or billiard, you know (s)he is using the long-scale. Likewise, if (s)he ever says "one billion eV (or 1 GeV)", you know (s)he is using the short scale. –  Ord Jul 4 '12 at 17:05