Work these calculation items the way the NCLEX expects: convert units first, round only at the end, and check that the answer makes clinical sense. Each one shows a worked solution.
1,000 mL of lactated Ringer's is to infuse over 10 hours by gravity. The drop factor is 20 gtt/mL. How many drops per minute should the nurse regulate?
Answer: 33 gtt/min
(1,000 mL × 20 gtt/mL) ÷ 600 min = 20,000 ÷ 600 = 33.3, rounded to 33 gtt/min.
Source: Potter & Perry. Fundamentals of Nursing, 12th ed. (gravity drip rate)
Acetaminophen 15 mg/kg PO is prescribed for a child who weighs 18 kg. The liquid is labeled 160 mg/5 mL. How many mL should the nurse give?
Answer: 8.4 mL
Dose: 15 mg × 18 kg = 270 mg. Volume: (270 ÷ 160) × 5 mL = 8.4375, rounded to 8.4 mL.
Source: Pickar. Dosage Calculations; AAP acetaminophen dosing
Levothyroxine 0.1 mg PO daily is prescribed. The tablets available are 50 mcg each. How many tablets should the nurse give?
Answer: 2 tablets
0.1 mg = 100 mcg. 100 mcg ÷ 50 mcg = 2 tablets.
Source: Pickar. Dosage Calculations (metric conversions)
A heparin bolus of 80 units/kg IV is prescribed for a client who weighs 75 kg. The vial contains 5,000 units/mL. How many mL should the nurse give?
Answer: 1.2 mL
Dose: 80 units × 75 kg = 6,000 units. Volume: 6,000 ÷ 5,000 = 1.2 mL. Heparin is high-alert; get an independent double check.
Source: Pickar. Dosage Calculations; ISMP High-Alert Medications
An IV antibiotic in 100 mL of 0.9% sodium chloride is to infuse over 30 minutes. At what rate should the nurse set the pump?
Answer: 200 mL/hr
100 mL ÷ 0.5 hr = 200 mL/hr.
Source: Pickar. Dosage Calculations (IV piggyback rates)
Amoxicillin 40 mg/kg/day is prescribed, divided every 8 hours, for a child who weighs 15 kg. How many mg should the nurse give per dose?
Answer: 200 mg
Daily dose: 40 mg × 15 kg = 600 mg/day. Divided every 8 hours (3 doses): 600 ÷ 3 = 200 mg per dose.
Source: Pickar. Dosage Calculations (pediatric divided doses)
A diltiazem infusion contains 125 mg in 125 mL. The prescribed dose is 10 mg/hr. At what rate should the nurse set the pump?
Answer: 10 mL/hr
Concentration: 125 mg ÷ 125 mL = 1 mg/mL. Rate: 10 mg/hr ÷ 1 mg/mL = 10 mL/hr.
Source: Pickar. Dosage Calculations; FDA label: Diltiazem injection
An insulin infusion contains 100 units of regular insulin in 100 mL of 0.9% sodium chloride. The prescribed rate is 6 units/hr. At what rate should the nurse set the pump?
Answer: 6 mL/hr
Concentration: 100 units ÷ 100 mL = 1 unit/mL. Rate: 6 units/hr ÷ 1 unit/mL = 6 mL/hr.
Source: Pickar. Dosage Calculations; ISMP High-Alert Medications
A nitroglycerin infusion contains 50 mg in 250 mL of D5W. The prescribed dose is 10 mcg/min. At what rate in mL/hr should the nurse set the pump?
Answer: 3 mL/hr
Concentration: 50 mg ÷ 250 mL = 0.2 mg/mL = 200 mcg/mL. Dose: 10 mcg/min × 60 = 600 mcg/hr. Rate: 600 ÷ 200 = 3 mL/hr.
Source: Pickar. Dosage Calculations (mcg/min titrations)
Dobutamine 250 mg in 250 mL D5W is prescribed at 5 mcg/kg/min for a client who weighs 80 kg. At what rate in mL/hr should the nurse set the pump?
Answer: 24 mL/hr
Concentration: 250 mg ÷ 250 mL = 1 mg/mL = 1,000 mcg/mL. Dose: 5 × 80 = 400 mcg/min × 60 = 24,000 mcg/hr. Rate: 24,000 ÷ 1,000 = 24 mL/hr.
Source: Pickar. Dosage Calculations (weight-based titrations)
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