10^{24} 
yotta 
Y 
10^{21} 
zetta 
Z 
10^{18} 
exa 
E 
10^{15} 
peta 
P 
10^{12} 
tera 
T 
10^{9} 
giga 
G 
10^{6} 
mega 
M 
10^{3} 
kilo 
k 
10^{2} 
hecto 
h 
10^{1} 
deka 
da 
10^{1} 
deci 
d 
10^{2} 
centi 
c 
10^{3} 
milli 
m 
10^{6} 
micro 
m 
10^{9} 
nano 
n 
10^{12} 
pico 
p 
10^{15} 
femto 
f 
10^{18} 
atto 
a 
10^{21} 
zepto 
z 
10^{24} 
yocto 
y 
Notice
All of the prefix names start with small letters.
Abbreviations for Powers of 10^{6} and greater are abbreviated with capital letters.
Powers greater than or equal to 10^6 end in "a". mega meter is Mm.
Powers 10^6 or less end in an "o," A nano meter is nm.
For the largest and smallest divisions divide the power by 3 the resulting number will remind you of the name of the prefix.
10^{24 }take 24 divide by 3 = 8 think octo remember yocto, yotta
and in the opposite direction
exa remember hexa or 6 multiply by 3 = 18 so 10^{18}
Scientific Explorations with Paul Doherty 

6 May 99 