PrefixesHere are the metric prefixes, with their numerical equivalents stated in the American system for naming large numbers: 

yotta- (Y-) 	10 24	1 septillion	
zetta- (Z-)	10 21	1 sextillion 	
exa- (E-) 	10 18	1 quintillion	
peta- (P-) 	10 15	1 quadrillion	
tera- (T-)	10 12	1 trillion	
giga- (G-)	10 9	1 billion 	
mega- (M-) 	10 6	1 million 	
kilo- (k-)	10 3	1 thousand	
hecto- (h-)	10 2	1 hundred	
deka- (da-)**	10	1 ten	
deci- (d-)	10 -1	1 tenth 	
centi- (c-) 	10 -2	1 hundredth 	
milli- (m-)	10 -3	1 thousandth	
micro- (µ-)	10 -6	1 millionth	
nano- (n-)	10 -9	1 billionth 	
pico- (p-) 	10 -12	1 trillionth	
femto- (f-)	10 -15	1 quadrillionth	
atto- (a-)	10 -18	1 quintillionth	
zepto- (z-)	10 -21	1 sextillionth	
yocto- (y-) 	10 -24	1 septillionth	

**The SI Brochure spelling of this prefix is deca-, but the U.S. National Institute of Standards and Technology (NIST) recommends deka-. National variations in spelling of the prefixes are allowed by the SI. In Italian, for example, hecto- is spelled etto- and kilo- is spelled chilo-. The symbols, however, are the same in all languages, so dam (not dkm) is the symbol for the dekameter and km is the symbol for the Italian chilometro.