Metric Prefix Conversions Made Simple: Move the Decimal Point

When you need to express a quantity using a different metric prefix than the one originally used, the trick is simple: shift the decimal point to the right or left according to the distance between the two prefixes on the metric “number line.”

The number line is laid out from larger to smaller prefixes, left to right, so you can easily remember which direction to move the decimal point for any conversion.

Example 1: Convert 0.000023 amps to microamps.

0.000023 amps (no prefix)

From “none” to “micro” is 6 places to the right (10⁶), so we shift the decimal point 6 places to the right:

0.000023 amps = 23 µA.

Example 2: Convert 304,212 volts to kilovolts.

304,212 volts (no prefix)

From “none” to “kilo” is 3 places to the left (10³), so shift the decimal point 3 places to the left:

304,212 V = 304.212 kV.

Example 3: Convert 50.3 MΩ to milli‑ohms.

50.3 MΩ (mega = 10⁶)

From “mega” to “milli” is 9 places to the right (10⁶ → 10⁻³), so shift the decimal point 9 places to the right:

50.3 MΩ = 50,300,000,000 mΩ.

Quick Review

• Use the metric prefix number line to determine the direction and magnitude of the decimal‑point shift.
• A number written without a decimal point is treated as if the point were immediately to the right of the last digit (e.g., 436 is 436.).

Related Worksheets

• Ohm’s Law Worksheet
• Scientific Notation and Metric Prefixes Worksheet