Nursing Math Study Guide
Five “Rights” of Medication Administration
The right patient
The right drug
The right dose
The right route
The right time
Tips and Common Errors
- The metric system is used in hospitals, and common mistakes include using the weight
in pounds instead of kilograms, completing conversions incorrectly, or making a
calculation error.
- Complete any conversions first (pounds into kilograms, ounces into milliliters, etc.)
before solving the problem.
Common Conversions
1g = 1000 mg
1L = 1000 ml
1 kg = 2.2 lbs
1 oz = 30 ml
1 teaspoon= 5 ml
1 tablespoon = 15 ml
Mathematical Techniques
Let’s imagine that the dosing for medication A is 30 mg/kg. Our patient weighs 7 kg. How would we find the correct dose? This is where cross multiplication comes in:
30 mg x 30 mg x 7 kg = 210 /1 kg = 210 mg of medication
______ = ______
1kg 7kg
The other option is to multiply as shown in the second example.
Practice Problems
Problem 1:
A 3-year-old male comes into clinic with a temperature of 103F. He weighs 25 lbs and the
provider orders acetaminophen at 15 mg/kg. The concentration of the medication is listed on
the bottle as 160 mg/ 5 mg. How many milliliters of acetaminophen should the nurse
administer?
Problem 2:
Your two-year-old patient with vesicoureteral reflux is admitted with pyelonephritis. The
physician orders cefepime 100 mg/kg/day in two divided doses. Your patient weighs 10.8 kg.
The concentration of the cefepime is 2 g/100 ml. How many milliliters of cefepime will you
administer to your patient for each dose?
Problem 3:
Your three-year-old patient is prescribed amoxicillin 25 mg/kg/day in two divided doses for otitis media. She weighs 30.6 lbs. The concentration of the amoxicillin suspension is 250mg per teaspoon. How many ml of amoxicillin should the parents give to the patient for each dose?
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