How to Convert SI Prefixes
- 1). Write down the initial and final SI units that you want to convert between, including their prefixes. For example, you might want to know how many millimeters (mm) are in a kilometer (km), so you are converting between an initial prefix of milli and a final prefix of kilo.
- 2). Using a standard list or table of SI prefix factors, find the magnitude factors for both the initial and final prefixes. There are many Internet and print resources that give these factors. The factor for kilo is 1000, meaning that a kilometer is 1000 meters, while the factor for milli is 0.001, meaning that a millimeter is 0.001 meters.
- 3). Divide the magnitude factor for the final prefix by the factor for the initial prefix. This is the conversion factor between the two prefixes. In the example, you would divide the factor for kilo by the factor for milli, which would give 1000/0.001 = 1,000,000. This tells you that there are 1,000,000 millimeters in a kilometer.
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