International System Prefixes
The SI prefixes are used to name multiples and submultiples of any SI unit, whether they are base or derived units. These prefixes are placed before the name of the unit to indicate the decimal multiple or submultiple of it; similarly, prefix symbols precede unit symbols.
The SI prefixes are officially set by the International Bureau of Weights and Measures (Bureau International des Poids et Mesures), according to the following table:
| 1000n | 10n | Prefix | Symbol | Short scale | Long scale | Decimal equity in the prefixes of the International System | Allocation |
|---|---|---|---|---|---|---|---|
| 100010 | 1030 | quetta- | Q | Nonillion | Quintillón | 1 000 000 000 000 000 000 000 000 | 2022 |
| 10009 | 1027 | ronna- | R | Eighth | Mil cuatrillones | 1 000 000 000 000 000 000 000 000 | 2022 |
| 10008 | 1024 | Yotta- | And | Septillion | Cuatrillón | 1 000 000 000 000 000 000 000 | 1991 |
| 10007 | 1021 | zetta- | Z | Sextillion | A thousand trillions | 1 000 000 000 000 000 000 | 1991 |
| 10006 | 1018 | exa... | E | Quintillón | Trillion | 1 000 000 000 000 000 000 | 1975 |
| 10005 | 1015 | peta... | P | Cuatrillón | A billion. | 1 000 000 000 000 000 | 1975 |
| 10004 | 1012 | tera- | T | Trillion | Billion | 1 000 000 000 000 | 1960 |
| 10003 | 109 | giga- | G | Billion | billion / billion | 1 000 000 000 | 1960 |
| 10002 | 106 | mega- | M | Million | 1 000 | 1960 | |
| 10001 | 103 | kilo- | k | Mil / Millar | 1 000 | 1795 | |
| 10002/3 | 102 | Hecto- | h | Hundred / Hundred | 100 | 1795 | |
| 10001/3 | 101 | deca- | da | Ten / Ten | 10 | 1795 | |
| 10000 | 100 | No prefix | One / Unit | 1 | |||
| 1000−1/3 | 10−1 | deci- | d | Tenth | 0.1 | 1795 | |
| 1000−2/3 | 10−2 | centi- | c | Centésimo | 0.01 | 1795 | |
| 1000−1 | 10−3 | mili- | m | A thousandth | 0.001 | 1795 | |
| 1000−2 | 10−6 | micro- | μ | Millions | 0.000 001 | 1960 | |
| 1000−3 | 10−9 | nano- | n | Billionth | One billion dollars | 0.000 000 001 | 1960 |
| 1000−4 | 10−12 | peak... | p | Trillonéimo | Billionth | 0.000 000 000 001 | 1960 |
| 1000−5 | 10−15 | femto- | f | Cuatrillonésimo | Milbillonésimo | 0.000 000 000 000 001 | 1964 |
| 1000−6 | 10−18 | Atto- | a | Quintillonésimo | Trillonéimo | 0.000 000 000 000 000 000 001 | 1964 |
| 1000−7 | 10−21 | zepto- | z | Sextillonésimo | Miltrillonésimo | 0.000 000 000 000 000 000 000 001 | 1991 |
| 1000−8 | 10−24 | Icto- | and | Septillonésimo | Cuatrillonésimo | 0.000 000 000 000 000 000 000 000 000 001 | 1991 |
| 1000−9 | 10−27 | red. | r | Eighth. | Milcuatrillonésimo | 0.000 000 000 000 000 000 000 000 000 000 001 | 2022 |
| 1000−10 | 10−30 | Quecto- | q | Nonillonésimo | Quintillonésimo | 0.000 000 000 000 000 000 000 000 000 000 000 001 | 2022 |
Notes on its use
- You can't put two or more prefixes together: for example, 10−9 meters you have to write them as 1 nm, not 1 mμm.
Employment outside the IS
The symbol "K" (capitalized) is often used to mean a multiple of a thousand; therefore, it can be written "salary of 40K" (of 40,000 euros) or "the problem of the year 2K".[citation needed] Despite the usual use, this use of the capital K is not correct in the SI, since it is the symbol for Kelvin units of temperature. The use of the abbreviation Ki is used to represent the binary prefix kibi (210 = 1024).
Proposed extensions
Continuing backwards in the alphabet, after zetta and yotta, among the proposals to name the next large numbers are the words xenta and xona (among others), the latter being a modification of the numerical suffix from Latin nona-; the proposal for the following small numbers would also begin with "x".
Summary of employment rules
In accordance with the general principles adopted by (ISO 31), the International Committee on Weights and Measures (CIPM) recommends that the following rules be observed when using the above prefixes: