Exa is a decimal unit prefix in the metric system denoting 10^{18} or 1000000000000000000. It was added as an SI prefix to the International System of Units (SI) in 1975,^{[1]} and has the unit symbol E.
Exa comes from the ancient Greek ἕξ héx, used as a prefix ἑξά- hexá-, meaning six (like hexa-), because it is equal to 1000^{6}.
Examples:
- The total storage needed by Gmail as of April 2012, ignoring backups and compression, is more than an exabyte (10,240 megabytes of storage per user multiplied by an estimated 260 million users)
- 1 EeV = 10^{18} electronvolts = 0.1602 joule
- United States electric energy consumption is about 15 exajoule per year
- 1 exasecond is approximately 32 billion years
- 0.43 Es ≈ the approximate age of the universe
- 1 exametre is approximately 110 light-years
- 1.6 Em is 172 ± 12.5 light years—diameter of Omega Centauri (one of the largest-known globular clusters, perhaps containing over a million stars)^{[2]}^{[3]}
- 150 exahashes/s is the calculation rate of the Bitcoin network ≈ 150000000000000000000 hashes per second as of January 2021^{[4]}
- 1.5 exaFLOPS is the compute performance of the upcoming 'Frontier' supercomputer built by AMD and Cray for Oak Ridge National Laboratory^{[5]}
Prefix | Base 10 | Decimal | English word | Adoption^{[nb 1]} | Etymology | |||
---|---|---|---|---|---|---|---|---|
Name | Symbol | Short scale | Long scale | Language | Derived word | |||
yotta | Y | 10^{24} | 1000000000000000000000000 | septillion | quadrillion | 1991 | Greek | eight^{[nb 2]} |
zetta | Z | 10^{21} | 1000000000000000000000 | sextillion | trilliard | 1991 | Latin | seven^{[nb 2]} |
exa | E | 10^{18} | 1000000000000000000 | quintillion | trillion | 1975 | Greek | six |
peta | P | 10^{15} | 1000000000000000 | quadrillion | billiard | 1975 | Greek | five^{[nb 2]} |
tera | T | 10^{12} | 1000000000000 | trillion | billion | 1960 | Greek | four^{[nb 2]}, monster |
giga | G | 10^{9} | 1000000000 | billion | milliard | 1960 | Greek | giant |
mega | M | 10^{6} | 1000000 | million | 1873 | Greek | great | |
kilo | k | 10^{3} | 1000 | thousand | 1795 | Greek | thousand | |
hecto | h | 10^{2} | 100 | hundred | 1795 | Greek | hundred | |
deca | da | 10^{1} | 10 | ten | 1795 | Greek | ten | |
10^{0} | 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, beak, little bit |
femto | f | 10^{−15} | 0.000000000000001 | quadrillionth | billiardth | 1964 | Danish | fifteen |
atto | a | 10^{−18} | 0.000000000000000001 | quintillionth | trillionth | 1964 | Danish | eighteen |
zepto | z | 10^{−21} | 0.000000000000000000001 | sextillionth | trilliardth | 1991 | Latin | seven^{[nb 2]} |
yocto | y | 10^{−24} | 0.000000000000000000000001 | septillionth | quadrillionth | 1991 | Greek | eight^{[nb 2]} |
See also
- Binary prefix
- Exabyte
- Exametre
- Metric prefix
- Orders of magnitude (numbers)
- Orders of magnitude (time)
References
- ^ "Resolution 10 of the 15th meeting of the CGPM (1975)". International Bureau of Weights and Measures. Retrieved 2012-04-18.
- ^ distance × sin( diameter_angle ), using distance of 5 kpc (15.8 ± 1.1 kly) and angle 36.3', = 172 ± 12.5 ly.
- ^ van de Ven, G.; van den Bosch, R. C. E.; Verolme, E. K.; de Zeeuw, P. T. (January 2006). "The dynamical distance and intrinsic structure of the globular cluster ω Centauri". Astronomy and Astrophysics. 445 (2): 513–543. arXiv:astro-ph/0509228. Bibcode:2006A&A...445..513V. doi:10.1051/0004-6361:20053061.
best-fit dynamical distance D=4.8±0.3 kpc ... consistent with the canonical value 5.0±0.2 kpc obtained by photometric methods
- ^ "Total Hash Rate". blockchain.com. Retrieved 2021-01-21.
- ^ Bright, Peter (2019-05-07). "Cray, AMD to build 1.5 exaflops supercomputer for US government". Ars Technica. Retrieved 2019-05-29.
- International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN 92-822-2213-6, archived (PDF) from the original on 2017-08-14
External links
Look up exa- in Wiktionary, the free dictionary. |