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Math for Nurses

System of Measurement

Health professionals use three systems of measurement: metric, apothecary, and the American system of measurement, known as the household system. Metrics are based on base ten, apothecary on roman numerals, and household on your basic teaspoon, gallon, and cup measurements. Health professionals need be familiar with all three as doctors write prescriptions using both the metric and apothecary systems and as patients need to be able to understand how to measure their prescriptions at home.It's important for all medical professionals to have an understanding of all three systems of measurement in order to perform conversions and administer doses.


Medicine is commonly prescribed in grams or grains. The health professional must be diligent in converting those measurements into the proper amount of liquid or solid medication that a patient requires. This takes converting from or within one or more of the three systems of measurements health professionals use: metric, apothecary, and household.


Knowledge of dosing requirements is something that every nurse muat master. Nurses must understand the relationships among the metric, apothecary and household systems of measurements, how to convert from one or more of them, and how to dole out the proper dosing of medication with that uniform knowledge in order to reduce medication errors.It is critical that all dosages be measured in the same units, as mixing measurement systems can severely alter the makeup of the medicine.

IV/IV Flow Rates

Parenteral or injection routes of administrating medicines are by syringe or intravenous (IV) drips. Syringes, commonly called needles or shots, can have different calibrations and volume especially when used to administer medication through an IV. Syringe calibrations must be looked at carefully in order to administer the proper volume of medication through an IV. It is extremely important to understand the three systems of measurements, what a calibration is, how to convert them and how to dose through syringes in order to obtain the correct drip rates for IVs.