# Rhagddodiad SI

Rhagddodiad SI| Math | rhagddodiad yr uned  |
| Y gwrthwyneb | non-SI unit prefix, binary prefix  |
| Yn cynnwys | quecto, ronto, yocto, zepto, atto, femto, pico, nano, micro, milli-, centi, deci, null morpheme, deca, hecto, kilo, mega, giga, tera, peta, exa, zetta, yotta, ronna, quetta  |
| Dynodwyr |
| Freebase | /M/06ny9  |
|  Ffeiliau perthnasol ar Gomin Wicimedia |

Rhagddodiad safonol wedi'i dderbyn gan system enwi rhyngwladol o'r enw System Rhyngwladol o Unedau (Ffrangeg: *Le Système international d'unités*; Saesneg: *International System of Units*) ydy **rhagddodiaid SI**, sydd wedi eu seilio ar saith prif uned o fesur ac ar hwylustod y rhif deg (10):

Rhagddodiaid a safonwyd i'w rhoi o flaen yr Unedau
| Lluoswm
 | Enw
 |  | deca-
 | hecto-
 | kilo-
 | mega-
 | giga-
 | tera-
 | peta-
 | exa-
 | zetta-
 | yotta-
 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Symbol
 |  | da
 | h
 | k
 | M
 | G
 | T
 | P
 | E
 | Z
 | Y
 |
| Ffactor
 | 100 | 101 | 102 | 103 | 106 | 109 | 1012 | 1015 | 1018 | 1021 | 1024 |
|  |
| Isddosbarthiad
 | Enw
 |  | deci-
 | centi-
 | milli-
 | micro-
 | nano-
 | pico-
 | femto-
 | atto-
 | zepto-
 | yocto-
 |
| Symbol
 |  | d
 | c
 | m
 | μ
 | n
 | p
 | f
 | a
 | z
 | y
 |
| Ffactor
 | 100 | 10−1 | 10−2 | 10−3 | 10−6 | 10−9 | 10−12 | 10−15 | 10−18 | 10−21 | 10−24 |

## Tabl manwl

Rhagddodiaid SI
| Rhagddodiad
 | Symbol
 | 1000m | 10n | Ffurf degol
 | Term Cymraeg
 | Term Saesneg
 | Derbyniwyd[1] |
| --- | --- | --- | --- | --- | --- | --- | --- |
| iota-
 | Y
 | 10008 | 1024 | 1000000000000000000000000 | Septiliwn
 | Septillion
 | 1991
 |
| seta-
 | Z
 | 10007 | 21 | 1000000000000000000000 | Secstiliwn
 | Sextillion
 | 1991
 |
| ecsa-
 | E
 | 10006 | 18 | 1000000000000000000 | Cwintiliwn
 | Quintillion
 | 1975
 |
| peta-
 | P
 | 10005 | 15 | 1000000000000000 | Cwadriliwn
 | Quadrillion
 | 1975
 |
| tera-
 | T
 | 10004 | 12 | 1000000000000 | Triliwn
 | Trillion
 | 1960
 |
| giga-
 | G
 | 10003 | 9 | 1000000000 | Biliwn
 | Billion
 | 1960
 |
| mega-
 | M
 | 10002 | 6 | 1000000 | Miliwn
 | Million
 | 1960
 |
| kilo-
 | k
 | 10001 | 3 | 1000 | Mil
 | Thousand
 | 1795
 |
| hecto-
 | h
 | 10002⁄3 | 2 | 100
 | Cant
 | Hundred
 | 1795
 |
| deca-
 | da
 | 10001⁄3 | 1 | 10
 | Deg
 | Ten
 | 1795
 |
|  |  | 10000 | 0 | 1
 | Un
 | One
 |  |
| deci-
 | d
 | 1000−1⁄3 | −1 | 0.1
 | Degfed
 | Tenth
 | 1795
 |
| centi-
 | c
 | 1000−2⁄3 | −2 | 0.01
 | Canfed
 | Hundredth
 | 1795
 |
| mili-
 | m
 | 1000−1 | −3 | 0.001
 | Milfed
 | Thousandth
 | 1795
 |
| micro-
 | μ
 | 1000−2 | −6 | 0.000001 | Miliynfed
 | Millionth
 | 1960[2] |
| nano-
 | n
 | 1000−3 | −9 | 0.000000001 | Biliynfed
 | Billionth
 | 1960
 |
| pico-
 | p
 | 1000−4 | −12 | 0.000000000001 | Triliynfed
 | Trillionth
 | 1960
 |
| femto-
 | f
 | 1000−5 | −15 | 0.000000000000001 | Cwadriliynfed
 | Quadrillionth
 | 1964
 |
| ato-
 | a
 | 1000−6 | −18 | 0.000000000000000001 | Cwintriliynfed
 | Quintillionth
 | 1964
 |
| septo-
 | z
 | 1000−7 | −21 | 0.000000000000000000001 | Chwetriliynfed
 | Sextillionth
 | 1991
 |
| iocto-
 | y
 | 1000−8 | −24 | 0.000000000000000000000001 | Heptriliynfed
 | Septillionth
 | 1991
 |
| 1. Cyflwynwyd y system ddegol am y tro cyntaf yn 1795 gyda dim ond chwe rhagddodiad. Mae'r dyddiadau eraill yn cyfeirio at y dyddiadau y cafodd y rhagddodiaid eraill eu derbyn yn swyddogol gan CGPM.
2. Yn 1948 cafodd y micron ei dderbyn gan y CGPM; yn 1967 penderfynwyd ei hepgor.
 |

## Gweler hefyd

* System Ryngwladol o Unedau

## Cyfeiriadau