What unit is not part of the metric system?

The ounce is not part of the metric system, which is a decimal-based system of measurement that includes units like millimeters, centimeters, and meters. The metric system is used worldwide for scientific and standard measurements, providing a uniform framework that makes calculations and conversions easier.

In contrast, the ounce is part of the imperial system, which is predominantly used in the United States and a few other countries for measuring weight or volume. The metric system consists of units based on powers of ten, such as millimeters (one-thousandth of a meter), centimeters (one-hundredth of a meter), and meters themselves, making it consistent and straightforward for users. Understanding the distinction between these systems is crucial for proper measurements in scientific contexts and daily life.