# SI Prefixes (in perspective)

Often times, values in physics are abbreviated using metric prefixes, or SI prefixes. I found this table the other night and thought it would be helpful to post, in that I'm sure I'm not the only one who gets these mixed up sometimes.

Thanks to wiki for this table:

[TABLE="class: wikitable, width: 0"]

[TR]

[TH="bgcolor: #CCCCFF, colspan: 2"]**Metric prefixes**[/TH]

[/TR]

[TR]

[TD][TABLE]

[TR]

[TH="bgcolor: #EEDDFF"]Prefix[/TH]

[TH="bgcolor: #EEDDFF"]Symbol[/TH]

[TH="bgcolor: #EEDDFF"]1000* ^{m}*[/TH]

[TH="bgcolor: #EEDDFF"]10* ^{n}*[/TH]

[TH="bgcolor: #EEDDFF"]Decimal[/TH]

[TH="bgcolor: #EEDDFF"]Short scale[/TH]

[TH="bgcolor: #EEDDFF"]Long scale[/TH]

[TH="bgcolor: #EEDDFF"]Since^{[n 1]}[/TH]

[/TR]

[TR]

[TD]yotta[/TD]

[TD="align: center"]Y[/TD]

[TD]1000^{8}[/TD]

[TD]10^{24}[/TD]

[TD="align: right"]1000000000000000000000000[/TD]

[TD]septillion[/TD]

[TD]quadrillion[/TD]

[TD]1991[/TD]

[/TR]

[TR]

[TD]zetta[/TD]

[TD="align: center"]Z[/TD]

[TD]1000^{7}[/TD]

[TD]10^{21}[/TD]

[TD="align: right"]1000000000000000000000[/TD]

[TD]sextillion[/TD]

[TD]trilliard[/TD]

[TD]1991[/TD]

[/TR]

[TR]

[TD]exa[/TD]

[TD="align: center"]E[/TD]

[TD]1000^{6}[/TD]

[TD]10^{18}[/TD]

[TD="align: right"]1000000000000000000[/TD]

[TD]quintillion[/TD]

[TD]trillion[/TD]

[TD]1975[/TD]

[/TR]

[TR]

[TD]peta[/TD]

[TD="align: center"]P[/TD]

[TD]1000^{5}[/TD]

[TD]10^{15}[/TD]

[TD="align: right"]1000000000000000[/TD]

[TD]quadrillion[/TD]

[TD]billiard[/TD]

[TD]1975[/TD]

[/TR]

[TR]

[TD]tera[/TD]

[TD="align: center"]T[/TD]

[TD]1000^{4}[/TD]

[TD]10^{12}[/TD]

[TD="align: right"]1000000000000[/TD]

[TD]trillion[/TD]

[TD]billion[/TD]

[TD]1960[/TD]

[/TR]

[TR]

[TD]giga[/TD]

[TD="align: center"]G[/TD]

[TD]1000^{3}[/TD]

[TD]10^{9}[/TD]

[TD="align: right"]1000000000[/TD]

[TD]billion[/TD]

[TD]milliard[/TD]

[TD]1960[/TD]

[/TR]

[TR]

[TD]mega[/TD]

[TD="align: center"]M[/TD]

[TD]1000^{2}[/TD]

[TD]10^{6}[/TD]

[TD="align: right"]1000000[/TD]

[TD="colspan: 2, align: center"]million[/TD]

[TD]1960[/TD]

[/TR]

[TR]

[TD]kilo[/TD]

[TD="align: center"]k[/TD]

[TD]1000^{1}[/TD]

[TD]10^{3}[/TD]

[TD="align: right"]1000[/TD]

[TD="colspan: 2, align: center"]thousand[/TD]

[TD]1795[/TD]

[/TR]

[TR]

[TD]hecto[/TD]

[TD="align: center"]h[/TD]

[TD]1000^{2/3}[/TD]

[TD]10^{2}[/TD]

[TD="align: right"]100[/TD]

[TD="colspan: 2, align: center"]hundred[/TD]

[TD]1795[/TD]

[/TR]

[TR]

[TD]deca[/TD]

[TD="align: center"]da[/TD]

[TD]1000^{1/3}[/TD]

[TD]10^{1}[/TD]

[TD="align: right"]10[/TD]

[TD="colspan: 2, align: center"]ten[/TD]

[TD]1795[/TD]

[/TR]

[TR="bgcolor: #EEEEEE"]

[TD="colspan: 2"][/TD]

[TD]1000^{0}[/TD]

[TD]10^{0}[/TD]

[TD="align: center"]1[/TD]

[TD="colspan: 2, align: center"]one[/TD]

[TD]–[/TD]

[/TR]

[TR]

[TD]deci[/TD]

[TD="align: center"]d[/TD]

[TD]1000^{−1/3}[/TD]

[TD]10^{−1}[/TD]

[TD="align: left"]0.1[/TD]

[TD="colspan: 2, align: center"]tenth[/TD]

[TD]1795[/TD]

[/TR]

[TR]

[TD]centi[/TD]

[TD="align: center"]c[/TD]

[TD]1000^{−2/3}[/TD]

[TD]10^{−2}[/TD]

[TD="align: left"]0.01[/TD]

[TD="colspan: 2, align: center"]hundredth[/TD]

[TD]1795[/TD]

[/TR]

[TR]

[TD]milli[/TD]

[TD="align: center"]m[/TD]

[TD]1000^{−1}[/TD]

[TD]10^{−3}[/TD]

[TD="align: left"]0.001[/TD]

[TD="colspan: 2, align: center"]thousandth[/TD]

[TD]1795[/TD]

[/TR]

[TR]

[TD]micro[/TD]

[TD="align: center"]μ[/TD]

[TD]1000^{−2}[/TD]

[TD]10^{−6}[/TD]

[TD="align: left"]0.000001[/TD]

[TD="colspan: 2, align: center"]millionth[/TD]

[TD]1960[/TD]

[/TR]

[TR]

[TD]nano[/TD]

[TD="align: center"]n[/TD]

[TD]1000^{−3}[/TD]

[TD]10^{−9}[/TD]

[TD="align: left"]0.000000001[/TD]

[TD]billionth[/TD]

[TD]milliardth[/TD]

[TD]1960[/TD]

[/TR]

[TR]

[TD]pico[/TD]

[TD="align: center"]p[/TD]

[TD]1000^{−4}[/TD]

[TD]10^{−12}[/TD]

[TD="align: left"]0.000000000001[/TD]

[TD]trillionth[/TD]

[TD]billionth[/TD]

[TD]1960[/TD]

[/TR]

[TR]

[TD]femto[/TD]

[TD="align: center"]f[/TD]

[TD]1000^{−5}[/TD]

[TD]10^{−15}[/TD]

[TD="align: left"]0.000000000000001[/TD]

[TD]quadrillionth[/TD]

[TD]billiardth[/TD]

[TD]1964[/TD]

[/TR]

[TR]

[TD]atto[/TD]

[TD="align: center"]a[/TD]

[TD]1000^{−6}[/TD]

[TD]10^{−18}[/TD]

[TD="align: left"]0.000000000000000001[/TD]

[TD]quintillionth[/TD]

[TD]trillionth[/TD]

[TD]1964[/TD]

[/TR]

[TR]

[TD]zepto[/TD]

[TD="align: center"]z[/TD]

[TD]1000^{−7}[/TD]

[TD]10^{−21}[/TD]

[TD="align: left"]0.000000000000000000001[/TD]

[TD]sextillionth[/TD]

[TD]trilliardth[/TD]

[TD]1991[/TD]

[/TR]

[TR]

[TD]yocto[/TD]

[TD="align: center"]y[/TD]

[TD]1000^{−8}[/TD]

[TD]10^{−24}[/TD]

[TD="align: left"]0.000000000000000000000001[/TD]

[TD]septillionth[/TD]

[TD]quadrillionth[/TD]

[TD]1991[/TD]

[/TR]

[TR]

[TD="bgcolor: #EEEEEE, colspan: 8"]

**^**The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the CGPM.

[/TD]

[/TR]

[/TABLE]

[/TD]

[/TR]

[/TABLE]

These prefixes were developed to shorten extremely large or small values, such as the teeny tiny mass of an electron (9.11 E -31 kg, or .000911 yg) in contrast to the very large Avogadro's number (6.022E23 atoms, or .6022 yotta atoms in one mole). When tacked onto constants, sometimes we don't realize just how intense these prefixes really are. Here are a few examples to help grasp the largeness and smallness of these constants:

1. The Earth weighs 5,972 yotta grams, or 5.972E24 kg. It would take over 850 quintillion elephants to match this weight, or just over 81 moons.

2. The average mass of a human cell is 950 femto grams, or 9.5E-13 g. If you cut a penny into a trillion pieces of equal mass, the human cell would still have a lower mass than the penny bit. AND you would get arrested for defacing US currency. It's simply a lose-lose situation.

3. On earth, there are an estimated 7.059 G people (or 7.059 billion people). This is roughly 1000 times the number of pigeons in NYC. However, this is roughly 1/3 of the amount of hotdogs Americans consume in a year. (Yes really-- Americans chow down on an estimated 20 billion a year. That's about 70 hot dogs per person).

Hope that was enlightening if not helpful!

--Alpha Geek

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