SI prefix

    The standard metric prefixes used in the
   Système International d'Unités (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.

   (2009-09-01)