The “nano” and “pico” were not two ships sailed by Columbus.

So you have some idea that a 1.2 gigabyte hard drive on your computer is preferable to a 500 megabyte hard drive, but you’re not quite sure why. Or perhaps you’ve heard of curies, but don’t know if picocuries are bigger or smaller, or by how much. This table will help! We give the prefix name, multiple it represents, decimal equivalent, common symbol, and the name in plain old English. To practice using these prefixes, see the worksheet on converting units.

Multiple Decimal equivalent Prefix Symbol English
109
1,000,000,000 giga G billion
106
1,000,000 mega M million
103
1,000 kilo k thousand
102
100 hecto h hundred
101
10 deca/deka da ten
100
1 (none needed) (n/a) (n/a)
10-1
0.1 deci d tenth
10-2
0.01 centi c hundreth
10-3
0.001 milli m thousandth
10-6
0.000001 micro ยต (mu) millionth
10-9
0.000000001 nano n billionth
10-12 0.000000000001 pico p trillionth