If you have a hand-held transceiver that puts out 500 milliwatts, how many watts would this be?

The metric prefix 'milli-' (m) stands for one thousandth (1/1,000 or 0.001). To convert milliwatts to base watts, you must divide the number of milliwatts by 1,000. Dividing 500 milliwatts by 1,000 yields 0.5 watts. You can also think of this as moving the decimal point three places to the left. The other options result from moving the decimal point the wrong number of places. For example, 50 watts would be 50,000 milliwatts, and 5 watts would be 5,000 milliwatts.