A prescription indicates 0.3 g of a medication. How many mg does that equal?

To convert grams to milligrams, it's essential to know the relationship between these two units of measurement. Specifically, one gram is equal to 1,000 milligrams.

In this scenario, you are given a prescription for 0.3 grams of medication. To convert grams to milligrams, you would multiply the number of grams by 1,000:

0.3 grams × 1,000 mg/g = 300 mg.

This calculation indicates that 0.3 grams is equivalent to 300 milligrams, which is why this option is the correct answer. Understanding the metric system's prefixes can greatly aid in such conversions, enabling healthcare professionals to accurately interpret and administer medications based on prescriptions.