Scientific Notation and Significant Figures

The Metric System and Scientific Units of Measurement

In scientific laboratories and healthcare environments, standard communication depends on clear, shared units. The International System of Units (SI) is the standard metric system used in scientific measurements. By relying on standardized units, practitioners communicate what quantity was measured, although measured values still have uncertainty.

Different types of physical quantities rely on specific standard units within the metric system. In the metric system, the standard base unit for length is the meter. In chemistry, mass is standardly measured using the gram or the kilogram, depending on the scale of the material being evaluated. For fluids, the liter is the standard metric unit used to measure liquid volume. In everyday clinical and laboratory tasks, liquid volumes and spatial volumes are frequently connected through a direct equality: one milliliter is exactly equivalent in volume to one cubic centimeter.

Metric measurements are organized in increments of ten, making conversions straightforward. For instance, one liter equals 1,000 milliliters. When measuring mass, one kilogram equals 1,000 grams, one gram equals 1,000 milligrams, and one milligram equals 1,000 micrograms. Exact conversion factors within the same measurement system possess an infinite number of significant figures, which means that using these established relationships during unit conversions will never restrict or reduce the precision of your calculated values.

To express smaller or larger increments of these base units, standardized prefixes are attached to the unit name. Each prefix represents a specific multiplier written as an ordinary number or as a power of 10. The table below details these metric prefixes and their corresponding numerical values.