# SI Prefixes

Description of the SI prefix (units of measure) and SI prefix table

## SI-Prefixes

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.

## EDP Prefixes

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. 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.