Pharmacy Math and Statistics

Mathematical calculations are an essential part of the practice of pharmacy. Calculations are required not only for the accurate preparation and dispensing of medications, but also in the clinical realm of dose calculations and adjustments for individual patient needs. In this chapter, the common calculations encountered in the practice of pharmacy and their basic principles are summarized. This chapter assumes the background knowledge of mathematics such as mathematical functions with fractions, interconversions between fractions and decimals, natural and log exponential functions, and basic algebraic principles.1-4

The metric system of measurements is based on the principle of multiples of 10 to de­ne different ranges of quantities. Pre­xes in the metric system indicates that the mentioned numeric value be multiplied by nth power of 10. For example, the represented multiplier for the common pre­xes are: micro (pre­x: μ) is 10−6, milli (pre­x: m) is 10−3, centi (pre­x: c) is 10−2, deci (pre­x: d) is 10−1, deca (pre­x: dk) is 101, hecto (pre­x: h) is × 102, and kilo (pre­x: k) is × 103. Therefore, 1 kg = 1000 g = 1,000,000 mg = 1,000,000,000 μg.