Pharmacy technicians use exact measurements in their daily work. When you measure liquids for reconstituting solutions or calculate the amount of ingredients for compounding drugs and preparing parenteral intravenous solutions, the measurements and calculations must be precise. A mistake can have severe consequences, such as drug side effects, toxicity, or even death. Consider this comparison: achieving 90% on your pharmacy calculations test might be an exemplary grade of an A, while achieving a 90% rate of error-free medication preparations would definitely be a failing grade and could cause terrible harm.

Therefore, it is essential for pharmacy technicians to understand the basic measurement systems, mathematical calculations, and formulas used in pharmacy and other healthcare fields. A knowledge of the fundamentals is critical to minimizing medication errors involving dosage, flow rates, and concentrations. This chapter is merely an introduction to lay the foundation for these mathematical skills and provides an overview of the kinds of calculation skills you will need. Additional specific calculations used in compounding are covered in Chapter 10, “Extemporaneous Nonsterile Compounding,” and Chapter 13, “Sterile and Hazardous Compounding.” The retail math concepts of how to calculate markups and discounts and make change are covered in Chapter 9, “The Business of Community Pharmacy.”