Best way to show and switch between metric and US customary units for distance (km/mi)

1. What is the easiest way to convert between metric units?
2. What is the US customary unit for distance?

What is the easiest way to convert between metric units?

To convert from one unit to another within the metric system usually means moving a decimal point. If you can remember what the prefixes mean, you can convert within the metric system relatively easily by simply multiplying or dividing the number by the value of the prefix.

What is the US customary unit for distance?

In the US customary system of measurement, the most common units of distance are inches, feet, yards, and miles.