Description of the SI prefix (units of measure) and SI prefix table
Prefixes are used to express multiples or parts of units and avoiding numbers with many digits.
The common prefixes of mathematics are defined in the International System of Units (SI). They are based on powers of ten. The symbols of the SI prefixes are internationally uniform. The names differ, depending on the language.
The prefix symbol is written in front of the unit of measurement. For example, at \(km\), the kilo in front of the meter.
The following table shows the defined SI prefixes for mathematics
| Symbol | Name | Value | |||
| Y | Yotta | 1024 | 1.000.000.000.000.000.000.000.000 | Septillion | |
| Z | Zetta | 1021 | 1.000.000.000.000.000.000.000 | Sextillion | |
| E | Exa | 1018 | 1.000.000.000.000.000.000 | Quintillion | |
| P | Peta | 1015 | 1.000.000.000.000.000 | Quadrillion | |
| T | Tera | 1012 | 1.000.000.000.000 | Trillion | |
| G | Giga | 109 | 1.000.000.000 | Billion | |
| M | Mega | 106 | 1.000.000 | Million | |
| k | Kilo | 103 | 1000 | Thousand | |
| h | Hekto | 102 | 100 | Hundred | |
| da | Deka | 101 | 10 | Ten | |
| d | Dezi | 10-1 | 0.1 | Tenth | |
| c | Zenti | 10-2 | 0.01 | Hundredth | |
| m | Milli | 10-3 | 0,001 | Thousandth | |
| μ | Mikro | 10-6 | 0,000.001 | Millionth | |
| n | Nano | 10-9 | 0,000.000.001 | Billionth | |
| p | Piko | 10-12 | 0,000.000.000.001 | Trillionth | |
| f | Femto | 10-15 | 0,000.000.000.000.001 | Quadrillionth | |
| a | Atto | 10-18 | 0,000.000.000.000.000.001 | Quintillionth | |
| z | Zepto | 10-21 | 0,000.000.000.000.000.000.001 | Sextillionth | |
| y | Yokto | 10-24 | 0,000.000.000.000.000.000.000.001 | Septillionth | |
The micro-sign \(µ\) comes from the Greek script. Typewriting and printing often cause difficulties. In these cases is therefore often a \(u\) used.
In EDP, the use of prefixes is common, whose power is derived from the base 2. In 2000, a new designation was introduced, based on orders of magnitude, as in the table above. In general parlance, the definition has not yet prevailed. The names and symbols currently used instead show the following list.
| Y | Yotta | 280 | 1.208.925.819.614.629.174.706.176 | ||
| Z | Zetta | 270 | 1.180.591.620.717.411.303.424 | ||
| E | Exa | 260 | 1.152.921.504.606.846.976 | ||
| P | Peta | 250 | 1.125.899.906.842.624 | ||
| T | Tera | 240 | 1.099.511.627.776 | ||
| G | Giga | 230 | 1.073.741.824 | ||
| M | Mega | 220 | 1.048.576 | ||
| k | Kilo | 210 | 1.024 | ||
|
For the sake of completeness, the following table shows the IEC International standard IEC 60027-2 adopted names, which, however, have not prevailed in general parlance until today. |
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| Y | Yotta | 1024 | 1.000.000.000.000.000.000.000.000 | ||
| Z | Zetta | 1021 | 1.000.000.000.000.000.000.000 | ||
| Ei | Exbi | 260 | 1.152.921.504.606.846.976 | ||
| E | Exa | 1018 | 1.000.000.000.000.000.000 | ||
| Pi | Pebi | 250 | 1.125.899.906.842.624 | ||
| P | Peta | 1015 | 1.000.000.000.000.000 | ||
| Ti | Tebi | 240 | 1.099.511.627.776 | ||
| T | Tera | 1012 | 1.000.000.000.000 | ||
| Gi | Gibi | 230 | 1.073.741.824 | ||
| G | Giga | 109 | 1.000.000.000 | ||
| Mi | Mebi | 220 | 1.048.576 | ||
| M | Mega | 106 | 1.000.000 | ||
| Ki | Kibi | 210 | 1.024 | ||
| k | Kilo | 103 | 1.000 | ||
The micro-sign \(µ\) comes from the Greek script. Typewriting and printing often cause difficulties. In these cases is therefore often a \(u\) used.
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