Metric System Prefixes

Power	Symbol	Prefix
10²⁴	Y	"Yotta"
10²¹	Z	"Zetta"
10¹⁸	E	"Exa"
10¹⁵	P	"Peta"
10¹²	T	"Tera"
10⁹	G	"Giga"^*
10⁶	M	"Mega"
10³	k	"kilo"
10²	h	"Hecto"
10¹	da	"Deka"

Power	Symbol	Prefix
10^-1	d	"deci"
10^-2	c	"centi"
10^-3	m	"milli"
10^-6	µ	"micro"^§
10^-9	n	"nano"
10^-12	p	"pico"
10^-15	f	"femto"
10^-18	a	"atto"
10^-21	z	"zepto"
10^-24	y	"yocto"

^* Some pronounce it "Jiga" (soft "g"), while others prounounce it "Gig-uh" (with a hard "g"). Either is correct.
^§ µ is the greek letter "mu". If you don't have this symbol available you can sort-of get by using the Roman "u" instead, but keep in mind that "mu" is the greek letter for "m" not "u".

Upper and lower case are different. 1 Mm is significantly different from 1 mm!
More information on metric units of measurement and conversions is available from the National Institue of Standards and Technology (NIST)

Metric System Jokes

The following are not a part of the International System of Units (SI), but they may be amusing. :-)

(Note: 10^12 means 10 raised to the 12th power, and so on)

       10^12 Microphones = 1 Megaphone
	   10^6 bicycles = 2 megacycles
	 500 millenaries = 1 seminary
		10 cards = 1 decacards
	    1/2 lavatory = 1 demijohn
	      10^-6 fish = 1 microfiche
   453.6 graham crackers = 1 pound cake
	      10^12 pins = 1 terrapin
	  10^21 piccolos = 1 gigolo

	      10 rations = 1 decoration
	     100 rations = 1 C-ration
	   10 millipedes = 1 centipede
	  3 1/3 tridents = 1 decadent
	     10 monologs = 5 dialogues
	     5 dialogues = 1 decalogue
	     2 monograms = 1 diagram
	       8 nickles = 2 paradigms
	    2 snake eyes = 1 paradise
	       2 wharves = 1 paradox

    2000 mockingbirds = two kilomockingbirds   

         1 milliHelen = the amount of beauty required to launch a
         single ship