Si prefix

unit, standard
The standard metric prefixes used in the Système International d’Units (SI) conventions for scientific measurement.
Here are the SI magnifying prefixes, along with the corresponding binary interpretations in common use:
prefix abr decimal binary
yocto- 1000^-8 zepto- 1000^-7 atto- 1000^-6 femto- f 1000^-5 pico- p 1000^-4 nano- n 1000^-3 micro- * 1000^-2 * Abbreviation: Greek mu milli- m 1000^-1
kilo- k 1000^1 1024^1 = 2^10 = 1,024 mega- M 1000^2 1024^2 = 2^20 = 1,048,576 giga- G 1000^3 1024^3 = 2^30 = 1,073,741,824 tera- T 1000^4 1024^4 = 2^40 = 1,099,511,627,776 peta- 1000^5 1024^5 = 2^50 = 1,125,899,906,842,624 exa- 1000^6 1024^6 = 2^60 = 1,152,921,504,606,846,976 zetta- 1000^7 1024^7 = 2^70 = 1,180,591,620,717,411,303,424 yotta- 1000^8 1024^8 = 2^80 = 1,208,925,819,614,629,174,706,176
“Femto” and “atto” derive not from Greek but from Danish.
The abbreviated forms of these prefixes are common in electronics and physics.
When used with bytes of storage, these prefixes usually denote multiplication by powers of 1024 = 2^10 (K, M, G and T are common in computing). Thus “MB” stands for megabytes (2^20 bytes). This common practice goes against the edicts of the BIPM who deprecate the use of these prefixes for powers of two. The formal SI prefix for 1000 is lower case “k”; some, including this dictionary, use this strictly, reserving upper case “K” for multiplication by 1024 (KB is thus “kilobytes”).
Also, in data transfer rates the prefixes stand for powers of ten so, for example, 28.8 kb/s means 28,800 bits per second.
The unit is often dropped so one may talk of “a 40K salary” (40000 dollars) or “2 meg of disk space” (2*2^20 bytes).
The accepted pronunciation of the initial G of “giga-” is hard, /gi’ga/.
Confusing 1000 and 1024 (or other powers of 2 and 10 close in magnitude) – for example, describing a memory in units of 500K or 524K instead of 512K – is a sure sign of the marketroid. For example, 3.5″ microfloppies are often described as storing “1.44 MB”. In fact, this is completely specious. The correct size is 1440 KB = 1440 * 1024 = 1474560 bytes. Alas, this point is probably lost on the world forever.
In 1993, hacker Morgan Burke proposed, to general approval on Usenet, the following additional prefixes: groucho (10^-30), harpo (10^-27), harpi (10^27), grouchi (10^30). This would leave the prefixes zeppo-, gummo-, and chico- available for future expansion. Sadly, there is little immediate prospect that Mr. Burke’s eminently sensible proposal will be ratified.


Read Also:

  • Siprol

    Signal Processing Language. A DSP language. [“SIPROL: A High Level Language for Digital Signal Processing”, H. Gethoffer, Proc ICASSP-80, 1980, pp.1056-1059].

  • Sips

    verb (used with object), sipped, sipping. 1. to drink (a liquid) a little at a time; take small tastes of: He sipped the hot tea noisily. 2. to drink from a little at a time: The bird sipped the flower. 3. to take in; absorb: to sip knowledge at its source. verb (used without object), […]

  • Sipunculid

    noun 1. an invertebrate of the phylum Sipuncula, comprising the peanut worms. adjective 2. belonging or pertaining to the sipunculids.

  • Siqueiros

    noun 1. David Alfaro [dah-veeth ahl-fah-raw] /dɑˈvið ɑlˈfɑ rɔ/ (Show IPA), 1896–1974, Mexican painter. noun 1. David Alfaro (daˈβið alˈfaro). 1896–1974, Mexican painter, noted for his murals expressing a revolutionary message

Disclaimer: Si prefix definition / meaning should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. All content on this website is for informational purposes only.