Five kilometers is equal to 1.86 miles, but when rounded to the appropriate significant figures, that would be 2.0 miles. The conversion is performed by multiplying the number of kilometers by .62137, which is called a conversion factor.
If a conversion factor is not immediately known, conversions between the metric and imperial systems can be performed by breaking the conversion down into multiple steps. In this example, the answer could also be found by converting kilometers to meters and then meters to centimeters. From there, centimeters can be exactly converted to inches by dividing by 2.54, and then the result in inches can be converted into feet before the final step of converting from feet to miles.