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Math Prefixes for Electrical Measures

The 2022-2026 Technician License question pool inquires about those pesky math prefixes used in front of many electrical measurement quantities:


T5B03: Which is equal to one kilovolt?

A. One one-thousandth of a volt

B. One hundred volts

C. One thousand volts

D. One million volts


These types of Technician questions boil down to interpreting the prefix that’s added to the unit. In this case the unit is the electrical measure of electromotive force (EMF), volts. The prefix kilo has been added to the unit volts in the question. These kinds of mathematical prefixes are essentially multipliers, but you have to know by how much to multiply for a given prefix. Here is a list of the most common mathematical prefixes you’ll find in ham radio:

Math Prefix

Multiplier

Numerical Value

Decimal Value

pico

one trillionth

1/1,000,000,000,000

0.000000000001

nano

one billionth

1/1,000,000,000

0.000000001

micro

one millionth

1/1,000,000

0.000001

milli

one thousandth

1/1,000

0.001

unity (one), no multiplier

1

kilo

one thousand

1,000

mega

one million

1,000,000

giga

one billion

1,000,000,000

The prefix kilo means 1,000. So, a kilovolt is 1,000 volts. The correct answer to question T5B03, "Which is equal to one kilovolt?" is C. One thousand volts.


Converting Between Prefixes: You should also know that when converting between these prefixed units, the decimal point in a provided value shifts three positions for each “step” in the list of prefixes above. If you are stepping from a smaller prefix to a larger prefix (ex: converting from volts to kilovolts), move the decimal three positions left for each step. Conversely, if you are stepping from a larger prefix to a smaller one (ex: converting from microfarads to nanofarads), move the decimal three positions right for each step.


See the HamRadioSchool.com Technician License Course book Section 8.3 for more info on unit conversions in the question pool.


-- Stu WØSTU

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