Assistive Medication Administration Personnel (AMAP) Practice Exam

Which metric unit is equal to one thousandth of a gram?

1. Cubic centimeter

2. Microgram

3. Milligram

4. Gram

The correct answer is: Milligram

The milligram is the metric unit that is equal to one thousandth of a gram. In the metric system, the prefix "milli-" denotes a factor of one thousandth (1/1000). Therefore, one milligram (mg) is precisely 0.001 grams (g). This unit is commonly used in various fields including medicine and pharmacology to measure smaller quantities of substances. In contrast, other options represent different measurements or units. A cubic centimeter is a unit of volume, not mass, and is equivalent to one milliliter, while a microgram is one-millionth of a gram, a significantly smaller unit. The gram itself is the basic unit of mass in the metric system and does not reflect the thousandth measurement that defines a milligram. Understanding these distinctions is essential for effectively navigating measurements in pharmacological contexts.