Zetta-

Zetta is a decimal unit prefix in the metric system denoting a factor of 10²¹ or 1000000000000000000000. The prefix was added as an SI prefix to the International System of Units (SI) in 1991 and has the symbol Z.

Zetta is evocative of the Latin numeral septem, meaning "seven". Therefore it was used to denote the seventh power of 1000.

A prefix of the same value, hepta, was informally introduced a few years before the promulgation of zetta. It was formed from the Greek ἑπτά (hepta), also meaning "seven". Hepta never received official sanction and is obsolete. Zeta (ζήτα), although being the 6th letter of the Greek alphabet, denotes a value of seven (7) when used as a numeral.

Examples:

• The mass of Earth's atmosphere is approximately 5 zettagrams (Zg).
• The volume of seawater in the Earth's oceans is approximately 1.369 zettalitres (Zℓ).
• Avogadro's constant is 602.2 zettamol^-1 (Zmol^-1).
• A zettabyte (ZB) is a quantity of information or information storage capacity equal to 10²¹ bytes, 1000⁷ bytes, 1,000 exabytes or 1 sextillion bytes. The zebibyte (ZiB) is a related unit that uses a binary prefix, and means 1024⁷ bytes.

SI prefixes

Prefix 1000m 10n Decimal English word Adoption Name Symbol Short scale Long scale yotta Y  10008  1024 1000000000000000000000000  septillion  quadrillion 1991 zetta Z  10007  1021 1000000000000000000000  sextillion  thousand trillion or trilliard 1991 exa E  10006  1018 1000000000000000000  quintillion  trillion 1975 peta P  10005  1015 1000000000000000  quadrillion  thousand billion or billiard 1975 tera T  10004  1012 1000000000000  trillion  billion 1960 giga G  10003  109 1000000000  billion  thousand million or milliard 1960 mega M  10002  106 1000000             million 1960 (1873) kilo k  10001  103 1000             thousand 1960 (1795) hecto h  10002/3  102 100             hundred 1960 (1795) deca da  10001/3  101 10             ten 1960 (1795)  10000  100 1             one – deci d  1000−1/3  10−1 0.1             tenth 1960 (1795) centi c  1000−2/3   10−2 0.01             hundredth 1960 (1795) milli m  1000−1  10−3 0.001             thousandth 1960 (1795) micro μ  1000−2  10−6 0.000001             millionth 1960 (1873) nano n  1000−3  10−9 0.000000001  billionth  thousand millionth 1960 pico p  1000−4  10−12 0.000000000001  trillionth  billionth 1960 femto f  1000−5  10−15 0.000000000000001  quadrillionth  thousand billionth 1964 atto a  1000−6  10−18 0.000000000000000001  quintillionth  trillionth 1964 zepto z  1000−7  10−21 0.000000000000000000001  sextillionth  thousand trillionth 1991 yocto y  1000−8  10−24  0.000000000000000000000001  septillionth  quadrillionth  1991

See also

• Metric prefix

External links

• BIPM website