# Billionth

One **billionth** is the reciprocal of a billion, which means it has one of two definitions depending on whether the *long scale* or *short scale* definition is being used.^{[1]}

## Short scale

In the short (or American) scale, a billionth is equal to 0.000 000 001, or 1 x 10^{−9} in scientific notation. The prefix for this number is nano, and is abbreviated as "n" (for example, in electronics, one nanofarad would be written as 1 nF).^{[2]}

## Long scale

In the long (or English) scale, a billionth is equal to 0.000 000 000 001, or 1 x 10^{−12} in scientific notation. The prefix for this number is pico-, and is abbreviated as "p" (for example, in electronics, one picofarad would be written as 1 pF).^{[3]}

## References

- ↑ Gardner, J. W. (April 6, 1961), "How many is a billion?", Letters,
*New Scientist*: 888. - ↑ Carstairs-McCarthy, Andrew (2002),
*An Introduction to English Morphology: Words and Their Structure*, Edinburgh University Press, pp. 109–110, ISBN 9780748613267. - ↑ Bray, Charles (2001),
*Dictionary of Glass: Materials and Techniques*, University of Pennsylvania Press, p. 243, ISBN 9780812236194.

Preceded by Millionth |
Decimals |
Succeeded by Trillionth |

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