In summary, you investigated different ways to use dimensional analysis in order to solve problems that require you to convert measurement units between U.S. customary units and metric/SI units.

Dimensional analysis works because you multiply a given quantity times a unit rate that is equal to 1. In the equation above, 2.54 centimeters = 1 inch, so the ratio of these two quantities is 1. To convert 5 inches to centimeters, you can multiply 5 inches by “1,” but the “1” is disguised as a unit rate.

While people in the United States primarily rely on customary units (you buy gasoline by the gallon, apples by the pound, and mail letters by the ounce), people in most other countries use metric/SI units. Because so many industries are now global, it is important to be able to convert between customary units and metric/SI units.