Title: Metric System Prefixes
Course: BTEC-1100-301-302-303-F21 > Section: Module 1 - Calculations and Measurements

The metric units we will use most often in the lab are based on the gram (measure of mass, or “weight”) and liter (measure of volume).  If we wanted to measure a very small volume, perhaps 0. 1% of the volume of a 2 liter bottle of soda, that volume would be:

2 L x 0.1% = 0.002 L

0.002 is kind of an unwieldy number—there are lots of zeros to keep track of.
This is the beauty of the metric system: we have prefixes that allow us to do away with many of those zeros.  (There are more SI prefixes than are listed here, but these are the ones we commonly use in biotechnology.)

Prefix | Symbol | Meaning | Meaning | Example
kilo- | k | 1000 | 10^3 | 1 kg = 1000 g
(none) | (none) | 1 | 10^0 |
milli- | m | 1/1000 | 10^-3 | 1000 mL = 1 L
micro- | µ | 1/1,000,000 | 10^-6 | 1000 µL = 1 mL
nano- | n | 1/1,000,000,000 | 10^-9 | 1000 ng = 1 µg

Using the table above, we can see that:
2 L x 0.1% = 0.002 L = 2 x 10-3 L = 2 mL

Isn’t it easier to write (and say) 2 mL instead of 0.002 L?