SI prefix

An SI prefix is a prefix, that, when applied to a word, means to multiply that word by a particular power of ten. Examples of applications of SI prefixes include kilometer, megapixel, and gigabyte. These prefixes are often applied to units of measurement.

Prefixes

The standard large and small SI prefixes are given below.

Name	Value	Factor/Divider	Name	Value
deca-	10	ten	deci-	0.1
hecto-	100	hundred	centi-	0.01
kilo-	1000	thousand	milli-	0.001
mega-	106	million	micro-	10-6
giga-	109	billion	nano-	10-9
tera-	1012	trillion	pico-	10-12
peta-	1015	quadrillion	femto-	10-15
exa-	1018	quintillion	atto-	10-18
zetta-	1021	sextillion	zepto-	10-21
yotta-	1024	septillion	yocto-	10-24

Etymology

SI stands for "Système international", French for "international system".

Extensions

Andre Joyce's extension

Andre Joyce fabricated an extension to the system, noting that zetta and yotta seem related to sette (Italian "seven") and otto (Italian "eight.") Following the reverse-alphabet pattern, we have xova- \(= 10^{27}\), x + nove, and weica- \(= 10^{30}\), w + dieci. (The last letter has been changed to a to keep the pattern.) The pattern for the corresponding negative exponents, like deci-, centi-, and milli-, all end in -i.

From here, only the first syllable of the Italian number is used. We have:

• vunda- = \(10^{33}\), v + und(ici), vundi- = \(10^{-33}\)
• uda- = \(10^{36}\), u + (do)d(ici), udi- = \(10^{-36}\)
• treda- = \(10^{39}\), t + tred(ici), tredi- = \(10^{-39}\)
• satta- = \(10^{42}\), s + (qu)att(ordici), satti- = \(10^{-42}\)
• rinda- = \(10^{45}\), r + (qu)ind(ici), rindi- = \(10^{-45}\)
• qeda- = \(10^{48}\), q + (s)ed(ici), qedi- = \(10^{-48}\)
• pica- = \(10^{51}\), p + (d)ic(iasette), pici- = \(10^{-51}\)
• oca- = \(10^{54}\), o + (di)c(iotto), oci- = \(10^{-54}\)
• nica- = \(10^{57}\), n + (di)c(iannove), nici- = \(10^{-57}\)
• menta- = \(10^{60}\), m + (v)ent(i), menti- = \(10^{-60}\)

The system continues to zotta- = \(10^{255}\) and zotti- = \(10^{-255}\).

Jim Blowers' extension

Initially Jim Blowers, like Andre Joyce, followed reverse-alphabet pattern and extends his system up to vigintillion:

• xona- = 10²⁷
• weka- = 10³⁰
• vunda- = 10³³
• uda- = 10³⁶
• treda- = 10³⁹
• sorta- = 10⁴²
• rinta- = 10⁴⁵
• quexa- = 10⁴⁸
• pepta- = 10⁵¹
• ocha- = 10⁵⁴
• nena- = 10⁵⁷
• minga- = 10⁶⁰
• luma- = 10⁶³

However, recently he changed this system and proposed his own system of prefixes up to 10^3,000. Here is a list of his prefixes:

• nina- = 10²⁷
• tena- = 10³⁰
• tenakilo- = 10³³
• tenamega- = 10³⁶
• tenagiga- = 10³⁹
• tenatera- = 10⁴²
• tenapeta- = 10⁴⁵
• tenaexa- = 10⁴⁸
• tenazetta- = 10⁵¹
• tenayotta- = 10⁵⁴
• tenanina- = 10⁵⁷
• bitena- = 10⁶⁰
• bitenakilo- = 10⁶³
• quadtena- = 10¹²⁰
• huna- = 10³⁰⁰
• tousa- = 10^3,000

Hella-extension

Austin Sendek, a University of California student, started a (somewhat jocular) Facebook petition to make "hella-" the official SI prefix for 10²⁷. "Hella" is a slang term originating out of Northern California, meaning "a lot of" or "very". The term has not become official, but both Google and Wolfram|Alpha have adopted it into their calculator systems.

Other extensions

There are many other extensions to the SI prefixes, which are listed on the wiki's articles on extended SI prefixes - for example, see the article Prefix 10²⁷.

See also

Googological affixes

Suffixes: -teen · -ty · -plex · -illion · -yllion · -exian · -chime · -toll · -gong · -bong · -throng · -illiob
Prefixes: gar- · fz- · fuga- · megafuga- · booga- · trooga- · googo- · googolple-
SI prefixes: deca- · hecto- · kilo- · mega- · giga- · tera- · peta- · exa- · zetta- · yotta-
Obsolete SI prefixes: myria-
Extended SI prefixes: 1.001 · 1.01 · 1.1 · 1.5 · 2 · 3 · 666 · 10⁵ · 10⁷ · 10⁸ · 10¹⁰ · 10¹¹ · 10¹³ · 10¹⁴ · 10¹⁶ · 10¹⁷ · 10¹⁹ · 10²⁰ · 10²² · 10²³ · 10²⁵ · 10²⁷ · 10²⁸ · 10²⁹ · 10³⁰ · 10³¹ · 10³² · 10³³ · 10³⁴ · 10³⁵ · 10³⁶ · 10³⁹ · 10⁴² · 10⁴⁵ · 10⁴⁸ · 10⁵⁰ · 10⁵¹ · 10⁵⁴ · 10⁵⁷ · 10⁶⁰ · 10⁶³ · 10⁶⁶ · 10⁶⁹ · 10⁷² · 10⁷⁵ · 10⁷⁸ · 10⁸⁰ · 10⁸¹ · 10⁸⁴ · 10⁸⁷ · 10⁹⁰ · 10¹⁰⁰ · 10¹²⁰ · 10¹⁵⁰ · 10¹⁸⁰ · 10²¹⁰ · 10²⁴⁰ · 10²⁷⁰ · 10³⁰⁰ · 10⁶⁰⁰ · 10⁹⁰⁰ · 10¹²⁰⁰ · 10¹⁵⁰⁰ · 10¹⁸⁰⁰ · 10²¹⁰⁰ · 10²⁴⁰⁰ · 10²⁷⁰⁰ · 10³⁰⁰⁰ and higher