Write down the common metric measurements in order on a piece of paper. The metric measurements are expressed using a series of prefixes: kilo, hecto, deka, deci, centi and milli. The type of measurement is then added to the center of the scale, such as grams for weight, meters for length and liters for volume. For meters, the final measurement scale would read, "kilo, hecto, deka, meter, deci, centi milli."
Find out what you need to convert. Kilo is the largest measurement on the scale you created, and milli is the smallest. What you need to know is which way you're converting the metric measurements. You can convert from a smaller unit to a larger, such as from milligrams to decigrams, or from a larger to a smaller unit, such as from a hectoliter to a centiliter.
Write down the unit you're converting on your paper. For example, you might write down 500.00 decimeters, and plan to convert it to kilometers.
Count how many places the unit you're starting is away from the unit you're converting it to and pay attention to which way you're moving. For example, decimeters and kilometers are four spaces apart, meaning you need to move the decimal point over four spaces to convert from decimeters to kilometers. Since you're moving to the left on the scale, move the decimal to the right.
Move the decimal. Using the information you discovered above, 500.00 decimeters would become .05 kilometers because you need to move the decimal place on 500 to the left four spaces. If you were converting 5.00 kilometers to decimeters instead, you'd move the decimal the opposite way to get 50,000.00 decimeters.