# Peta-

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Peta () is a decimal unit prefix in the metric system denoting multiplication by 1015 (1000000000000000). It was adopted as an SI prefix in the International System of Units in 1975, [1] and has the symbol P.

## Contents

Peta is derived from the 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:

PrefixBase 1000Base 10 Decimal English wordAdoption [nb 1]
NameSymbol Short scale Long scale
yotta Y 10008  1024 1000000000000000000000000 septillion quadrillion1991
zetta Z 10007  1021 1000000000000000000000 sextillion trilliard1991
exa E 10006  1018 1000000000000000000 quintillion trillion1975
peta P 10005  1015 1000000000000000 quadrillion billiard1975
tera T 10004  1012 1000000000000 trillion billion1960
giga G 10003  109 1000000000 billion milliard1960
mega M 10002  106 1000000 million1873
kilo k 10001  103 1000 thousand1795
hecto h 10002/3  102 100 hundred1795
deca da 10001/3  101 10 ten1795
10000  100 1 one
deci d 1000−1/3  10−1 0.1 tenth1795
centi c 1000−2/3   10−2 0.01 hundredth1795
milli m 1000−1  10−3 0.001 thousandth1795
micro μ 1000−2  10−6 0.000001 millionth1873
nano n 1000−3  10−9 0.000000001 billionth milliardth1960
pico p 1000−4  10−12 0.000000000001 trillionth billionth1960
femto f 1000−5  10−15 0.000000000000001 quadrillionth billiardth1964
atto a 1000−6  10−18 0.000000000000000001 quintillionth trillionth1964
zepto z 1000−7  10−21 0.000000000000000000001 sextillionth trilliardth1991
yocto y 1000−8  10−24  0.000000000000000000000001 septillionth quadrillionth1991
1. Prefixes adopted before 1960 already existed before SI. 1873 was the introduction of the CGS system.