From Wikipedia, the free encyclopedia
zetta- (symbol Z) is an SI prefix in the SI (system of units) denoting 1021 or 1 000 000 000 000 000 000 000.
Adopted in 1991, it comes from the Latin septem, meaning seven, because it is equal to 10007.
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. It never received official sanction and is now obsolete.
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10000 100 (none) (none) NA One 1
1000−1/3 10−1 deci- d 1795 Tenth 0.1
1000−2/3 10−2 centi- c 1795 Hundredth 0.01
1000−1 10−3 milli- m 1795 Thousandth 0.001
1000−2 10−6 micro- µ 1960[2] Millionth 0.000 001
1000−3 10−9 nano- n 1960 Billionth Milliardth 0.000 000 001
1000−7 10−21 zepto- z 1991 Sextillionth Trilliardth 0.000 000 000 000 000 000 001
1000−8 10−24 yocto- y 1991 Septillionth Quadrillionth 0.000 000 000 000 000 000 000 001
The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM. The 1948 recognition of the micron by the CGPM was abrogated in 1967.
