What is the prefix for a factor of 10^-3?

The prefix that represents a factor of 10^-3 is "milli." In the metric system, "milli" indicates one thousandth of a unit. Therefore, when you see "millimeter," for example, it means one-thousandth of a meter. This understanding is important in various scientific contexts where precise measurements are required.

In comparison, the other prefixes have different values: "deci" represents 10^-1 or one-tenth, "centi" stands for 10^-2 or one-hundredth, and "pico" corresponds to 10^-12 or one trillionth. This differentiation among prefixes is essential for accurately interpreting and using measurements in scientific communication.