Wikipedia:
Non-SI unit prefixes |
There exist several unit prefixes used like the SI prefixes, but that are not part of the SI system.
Some of these were never part of any actual system of measurement. A few were proposals that were rejected. None are in common use, and many of the powers of ten they represent are already taken by SI prefixes. Sometimes a prefix is simply mistaken; dk has been passed off as an abbreviation for deka.
One such prefix is bronto, used in the fake term brontobyte. References on the World Wide Web suggest meanings of the bronto prefix to be variously any of 1015, 1021, 1024, or 1027. SI has already produced standard prefixes for 1015 (peta), 1021 (zetta) and 1024 (yotta).
Proposed and unofficial prefixes
There are many other unofficial prefixes. Some of them appear to come from a numerical Greek root indicating the power of 1000 the prefix means. Others are based on the names of the Marx Brothers. These prefixes are as follows:
| Prefix | Purported meaning |
|---|---|
| udeka- (U) | 1036 |
| udekta- (U) | 1036 |
| una- | 1033 |
| vendeka- (V) | 1033 |
| weka- (W)[1] | 1030 |
| wekta- (W) | 1030 |
| decetta- | 1030 |
| dea- | 1030 |
| grouchi- | 1030 |
| nea- | 1027 |
| xenna- (X) | 1027 |
| xenta- (X) | 1027 |
| novetta- | 1027 |
| harpi- | 1027 |
| lotta- (L) | 1027 |
| nova- (N) | 1027 |
| taxo- (Tx)[2] | 1027 |
| otta- | 1024 |
| hepa- | 1021 |
| ento- | 10−21 |
| fito- | 10−24 |
| syto- | 10−27 |
| xenno- (x) | 10−27 |
| novemo- | 10−27 |
| empto- (e)[2][3] | 10−27 |
| harpo- "#wp-_note-Harpo-Groucho-Zeppo-Gummo-Chico">[4] | 10−27 |
| lotto- (l) | 10−27 |
| novo- (n) | 10−27 |
| millikan- (mkan) | 10−27 |
| tredo- | 10−30 |
| weko- (w) | 10−30 |
| decemo- | 10−30 |
| groucho- "#wp-_note-Harpo-Groucho-Zeppo-Gummo-Chico">[4] | 10−30 |
| revo- | 10−33 |
| vendeko- (v) | 10−33 |
| zeppo- "#wp-_note-Harpo-Groucho-Zeppo-Gummo-Chico">[4] | 10−33 |
| gummo- "#wp-_note-Harpo-Groucho-Zeppo-Gummo-Chico">[4] | 10−36 |
| chico- "#wp-_note-Harpo-Groucho-Zeppo-Gummo-Chico">[4] | 10−39 |
Obsolete prefixes
Some prefixes were used in older versions of the metric system but are not part of the modern metric system, the SI.
The prefixes 'myria' (ma or my, for 10000) and 'myrio' (mo, for 1/10000) came from the Greek μύριοι (mýrioi) 'ten thousand'. Part of the original metric system adopted by France in 1795, they were not retained when the SI prefixes were agreed internationally by the 11th CGPM in 1960.
They were rarely used, though the myriameter (10 km) is occasionally encountered in 19th-century train tariffs. In Sweden (and possibly other countries), the myriameter is still very common in everyday use, simplifying the way of denoting long distances (although not recognized or used officially). In Swedish, this unit is called 'mil', not seldom causing confusion when Swedes use the English word 'mile' (incorrectly) as a direct translation.
Of units customarily used in trade in France, the myriagramme (10 kg) was the metric replacement for the avoirdupois unit of the quarter (25 pounds) (whereas the Myriogramme is also a genus of seaweed).
Also obsolete are metric double prefixes, such as those formerly used in micromicrofarads, hectokilometres, micromillimetres, and so on.
Proposed systems
A proposal by Jim Blowers describes the naming scheme as follows:
zetta is Z + -etta, which is an alteration of septi-, meaning 7, as 21 is 7 groups of three. yotta is Y + -otta, an alteration of octo-, meaning 8. The pattern here is that we go backwards from the end of the alphabet, starting with z then y, and we follow it up with an alteration of the Greek or Latin for the next number. According to this pattern, the next ending should be xona-, since X comes before Y in the alphabet, and 9 is noni- in Latin. Similarly, 1030 should be weka-, since W precedes X and 10 is deka in Greek.
| Factor | Name | Symbol | Factor | Name | Symbol | |
|---|---|---|---|---|---|---|
| 10−1 | deci- | d | 101 | deca- | da | |
| 10−2 | centi- | c | 102 | hecto- | h | |
| 10−3 | milli- | m | 103 | kilo- | k | |
| 10−6 | micro- | μ | 106 | mega- | M | |
| 10−9 | nano- | n | 109 | giga- | G | |
| 10−12 | pico- | p | 1012 | tera- | T | |
| 10−15 | femto- | f | 1015 | peta- | P | |
| 10−18 | atto- | a | 1018 | exa- | E | |
| 10−21 | zepto- | z | 1021 | zetta- | Z | |
| 10−24 | yocto- | y | 1024 | yotta- | Y | |
| 10−27 | xonto- | x | 1027 | xona- | X | |
| 10−30 | wekto- | w | 1030 | weka- | W | |
| 10−33 | vunkto- | v | 1033 | vunda- | V | |
| 10−36 | unto- | u | 1036 | uda- | U | |
| 10−39 | trekto- | td | 1039 | treda- | TD | |
| 10−42 | sotro- | s | 1042 | sorta- | S | |
| 10−45 | rimto- | r | 1045 | rinta- | R | |
| 10−48 | quekto- | q | 1048 | quexa- | Q | |
| 10−51 | pekro- | pk | 1051 | pepta- | PP | |
| 10−54 | otro- | o | 1054 | ocha- | O | |
| 10−57 | nekto- | nk | 1057 | nena- | N | |
| 10−60 | mikto- | mi | 1060 | minga- | MI | |
| 10−63 | lunto- | l | 1063 | luma- | L |
There have also been proposals to use the units of one of these systems with prefixes of a different base than ten, e.g. binary, duodecimal or hexadecimal.
References
External links
- Proposal to extend system of units from 10−63 to 1063
- BBC article suggesting that a brontobyte is 1027 bytes
- Sybase article suggesting that a brontobyte is 1024 or 1027 bytes (Note article's table a few pages down. Note also it mistakenly places 1 terabyte = 1,000 megabytes. It should be 1 terabyte = 1,000 gigabytes. Also yottabyte is shown incorrectly as zottabyte. With those corrections, it also is clearly 1027.)
- Article suggesting that a brontobyte is 1021 bytes
- Article suggesting that a brontobyte was 1015 bytes before the creation of the prefix peta- (Article is of dubious authority... suggests that Greek letters ν, π, and φ are SI prefixes for nano-, pico-, and femto-, instead of n, p, and f.)
- Article suggesting that brontobyte is 1027 bytes
- Moerner Lab Single-Molecule Research Page (Jokingly defines 1 guacamole = 1 / (Avocado's number) of moles. Scientific paper with reference)
- Jargon file entry for "quantifiers" Claims that groucho, harpo, grouchi, and harpi (based on the Marx Brothers' names) have gained the general approval of Usenet.
- vendeka.org website Support for vendeka = 1033
- Final Answers: Measurement and Units Large table of units
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