How many grains of codeine are in each tablet of Tylenol #3, if each tablet contains 30 mg of codeine?

To determine how many grains of codeine are in a tablet of Tylenol #3, it's important to understand the conversion between milligrams and grains. One grain is equivalent to approximately 64.8 milligrams.

In this case, since each tablet contains 30 mg of codeine, to convert milligrams to grains, you use the following calculation:

30 mg ÷ 64.8 mg/grain ≈ 0.462 grains.

This value can be rounded to approximately 1/2 grain. This aligns with the information provided for the correct choice, which highlights that 30 mg of codeine translates closely to 1/2 grain when using standard conversion factors.

Therefore, recognizing this conversion factor is crucial for understanding how much of a substance is in a given medication dosage, which is a fundamental aspect of pharmacy calculations.