Sometimes the dosage of a drug prescribed by a doctor does not exactly match the amount of the drug contained in one pill or a standard liquid measure. In these cases, the pharmacy technician must perform precise calculations so he can tell patients how to make sure they take the proper dosage. Pharmacy technician math calculations are simple to understand when you know the elements of the equations.

Understand the important information on the prescription. For tablets, capsules, liquid medications and injections, you need to know the prescribed dosage.

Identify the key information on the medication label. Tablet and capsule medication labels tell you how much medication is in each tablet or capsule; liquid medication labels tell you how much medication is in a given amount of the liquid; and injectable medication labels tell you how much medication is in a given amount of the injectable solution.

Make unit conversions, if necessary. If the prescribed dosage of a drug that comes in tablet form is 2 g and each tablet contains 500 mg of medication, you need to either convert the dosage (2 g) to milligrams (2000 mg), or convert the tablets (500 mg) to grams (0.5 g).

Set up and calculate the equation. The components of a pharmacy technician drug dosage calculation are simple. For a liquid or injectable medication, simply multiply the ordered dose by the amount of liquid in which a standard dose is suspended, and then divide the result by the standard dose. The result is the amount of medication that should be administered. For a medication in tablet or capsule form, divide the ordered dose by the amount of the drug contained in one tablet or capsule. The result is the number of tablets or capsules that should be administered.