How many millivolts equal two volts?

The metric prefix 'milli' means one-thousandth of a base unit (10^-3). This tells us that it takes 1,000 millivolts (mV) to equal exactly one volt (V). When converting from a larger base unit (volts) to a smaller sub-unit (millivolts), you must multiply the number by 1,000. Multiplying 2 volts by 1,000 gives 2,000 mV. The distractor 0.002 mV comes from mistakenly dividing by 1,000 instead of multiplying, while 2,000,000 mV uses the conversion factor for 'micro', not 'milli'.