Peta-

This article is about the SI prefix. For other uses, see Peta (disambiguation).

Peta (/ˈpɛtə/) is a decimal unit prefix in the metric system denoting multiplication by one quadrillion, or 10¹⁵ (1000000000000000). It was adopted as an SI prefix in the International System of Units in 1975, and has the symbol P.

Peta is derived from the ancient Greek πέντε, meaning "five". It denotes the fifth power of 1000 (1000⁵). It is similar to the prefix penta ("five"), but without the letter n (on the analogy of the prefix tera [from the Greek for "monster"] for 1000⁴ looking like tetra- ["four"] with a letter missing).

Examples:

• 1 petametre = 10¹⁵ metres
• 1 petasecond = 10¹⁵ seconds (31.7 million years)
• 1 petahertz = 10¹⁵ cycle per second. Visible light is around 0.5 PHz.
• 1 petabyte = 10¹⁵ bytes
• the mass–energy equivalence is 89.9 PJ/kg
• 1 light-year = 9.461 Pm

SI prefixes

Prefix		Base 10	Decimal	English word		Adoption	Etymology
Name	Symbol			Short scale	Long scale		Language	Source word
yotta	Y	1024	1000000000000000000000000	septillion	quadrillion	1991	Latin	eight
zetta	Z	1021	1000000000000000000000	sextillion	trilliard	1991	Latin	seven
exa	E	1018	1000000000000000000	quintillion	trillion	1975	Greek	six
peta	P	1015	1000000000000000	quadrillion	billiard	1975	Greek	five
tera	T	1012	1000000000000	trillion	billion	1960	Greek	four, monster
giga	G	109	1000000000	billion	milliard	1960	Greek	giant
mega	M	106	1000000	million		1873	Greek	great
kilo	k	103	1000	thousand		1795	Greek	thousand
hecto	h	102	100	hundred		1795	Greek	hundred
deca	da	101	10	ten		1795	Greek	ten
		100	1	one		–
deci	d	10−1	0.1	tenth		1795	Latin	ten
centi	c	10−2	0.01	hundredth		1795	Latin	hundred
milli	m	10−3	0.001	thousandth		1795	Latin	thousand
micro	μ	10−6	0.000001	millionth		1873	Greek	small
nano	n	10−9	0.000000001	billionth	milliardth	1960	Greek	dwarf
pico	p	10−12	0.000000000001	trillionth	billionth	1960	Spanish	peak, a little bit
femto	f	10−15	0.000000000000001	quadrillionth	billiardth	1964	Danish	fifteen, Fermi
atto	a	10−18	0.000000000000000001	quintillionth	trillionth	1964	Danish	eighteen
zepto	z	10−21	0.000000000000000000001	sextillionth	trilliardth	1991	Latin	seven
yocto	y	10−24	0.000000000000000000000001	septillionth	quadrillionth	1991	Latin	eight

See also

• Metric prefix
• Binary prefix

External links

• BIPM website