Numeracy & Drug Calculations
35 free practice questions with explanations
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PassNova has 35 free NMC CBT (Overseas Nurses) practice questions on Numeracy & Drug Calculations, each with a clear explanation. Practise them in the browser with instant feedback — 100% free, no sign-up, on any device. Updated for 2026.
Numeracy & Drug Calculations: example questions & answers
35 worked examples with answers and explanations below. Practise them in the browser with instant feedback on every answer.
A patient is prescribed paracetamol 1 g orally. The available tablets are 500 mg each. How many tablets should the nurse administer?
- A1 tablet
- B2 tablets✓
- C3 tablets
- D4 tablets
Answer: 1 g equals 1000 mg, and 1000 mg divided by 500 mg per tablet equals 2 tablets. This is a standard adult paracetamol dose.
A patient requires 500 mL of 0.9% sodium chloride to be infused over 4 hours via a gravity giving set delivering 20 drops per mL. What is the infusion rate in drops per minute (rounded to the nearest whole number)?
- A28 drops/min
- B42 drops/min✓
- C50 drops/min
- D63 drops/min
Answer: Volume 500 mL multiplied by 20 drops/mL equals 10000 drops, divided by 240 minutes equals approximately 42 drops per minute. This is the correct gravity infusion rate.
A child weighing 20 kg is prescribed a medicine at 5 mg/kg as a single dose. What total dose should be given?
- A25 mg
- B50 mg
- C100 mg✓
- D200 mg
Answer: 5 mg/kg multiplied by 20 kg equals 100 mg. Weight-based dosing requires multiplying the per-kilogram dose by the patient's weight.
A patient is prescribed 1.2 g of an antibiotic. The stock vial contains 600 mg in 5 mL once reconstituted. What volume should be drawn up?
- A5 mL
- B8 mL
- C10 mL✓
- D12 mL
Answer: 1.2 g equals 1200 mg, and using dose divided by stock multiplied by volume gives (1200/600) multiplied by 5 mL equals 10 mL. This is the correct volume to administer.
A 1000 mL bag of fluid is to run over 8 hours using a volumetric pump. What rate in mL/hour should the pump be set to?
- A100 mL/hour
- B125 mL/hour✓
- C150 mL/hour
- D175 mL/hour
Answer: 1000 mL divided by 8 hours equals 125 mL per hour. Volumetric pumps are programmed directly in millilitres per hour.
A patient is prescribed 75 mg of a drug available as 25 mg/mL oral solution. What volume should the nurse measure?
- A1 mL
- B2 mL
- C3 mL✓
- D4 mL
Answer: 75 mg divided by 25 mg/mL equals 3 mL. Dividing the prescribed dose by the concentration gives the required volume.
Insulin 12 units is prescribed. Using a U-100 insulin syringe, to which marking should the nurse draw up?
- A1.2 mL exactly
- B0.12 mL
- C12 units on the insulin syringe scale✓
- D120 units
Answer: Insulin must always be measured using an insulin syringe calibrated in units, drawing up to the 12-unit mark. Using a standard millilitre syringe for insulin is unsafe and never acceptable.
Convert 0.25 mg to micrograms.
- A0.025 micrograms
- B2.5 micrograms
- C25 micrograms
- D250 micrograms✓
Answer: 1 mg = 1,000 micrograms, so 0.25 mg x 1,000 = 250 micrograms.
Convert 1,500 micrograms to milligrams.
- A1.5 mg✓
- B15 mg
- C150 mg
- D1,500 mg
Answer: 1,000 micrograms = 1 mg, so 1,500 micrograms / 1,000 = 1.5 mg.
Convert 0.5 g to milligrams.
- A5 mg
- B50 mg
- C500 mg✓
- D5,000 mg
Answer: 1 g = 1,000 mg, so 0.5 g x 1,000 = 500 mg.
Digoxin 125 micrograms is prescribed. The tablets available are 62.5 micrograms each. How many tablets should be given?
- A1 tablet
- B2 tablets✓
- C3 tablets
- D4 tablets
Answer: Dose required / strength per tablet = 125 / 62.5 = 2 tablets.
Amoxicillin 250 mg is prescribed. The oral suspension contains 125 mg in 5 mL. What volume should be given?
- A10 mL✓
- B12.5 mL
- C20 mL
- D25 mL
Answer: Volume = (dose required / stock strength) x stock volume = (250 / 125) x 5 mL = 10 mL.
Furosemide 60 mg is prescribed. The tablets available are 40 mg each. How many tablets should be given?
- A1 tablet
- B1 and a half tablets✓
- C2 tablets
- D3 tablets
Answer: 60 mg / 40 mg per tablet = 1.5 tablets. Only split tablets that are scored and licensed to be split, and check with the pharmacist if unsure.
Morphine sulfate oral solution 10 mg in 5 mL is available. A dose of 2.5 mg is prescribed. What volume should be measured?
- A1.25 mL✓
- B2.5 mL
- C4 mL
- D5 mL
Answer: (2.5 / 10) x 5 mL = 0.25 x 5 mL = 1.25 mL. Use an oral syringe to measure a volume this small accurately.
A child weighing 18 kg is prescribed paracetamol 15 mg/kg as a single dose. What dose should be given?
- A150 mg
- B180 mg
- C225 mg
- D270 mg✓
Answer: 15 mg x 18 kg = 270 mg.
A child weighing 12 kg is prescribed a medicine at 30 mg/kg/day, given in three equally divided doses. What is each dose?
- A40 mg
- B120 mg✓
- C180 mg
- D360 mg
Answer: Daily dose = 30 mg x 12 kg = 360 mg. Divided into three doses: 360 / 3 = 120 mg per dose.
An injection of 5 mg is prescribed. The ampoule contains 10 mg in 1 mL. What volume should be drawn up?
- A0.5 mL✓
- B1 mL
- C2 mL
- D5 mL
Answer: (5 / 10) x 1 mL = 0.5 mL.
Heparin 5,000 units is prescribed subcutaneously. The vial contains 25,000 units per mL. What volume should be given?
- A0.02 mL
- B0.2 mL✓
- C0.5 mL
- D2 mL
Answer: (5,000 / 25,000) x 1 mL = 0.2 mL.
Gentamicin 120 mg is prescribed. The vial contains 40 mg per mL. What volume should be drawn up?
- A0.33 mL
- B1.2 mL
- C2.4 mL
- D3 mL✓
Answer: (120 / 40) x 1 mL = 3 mL.
Ondansetron 4 mg is prescribed. The ampoule contains 2 mg per mL. What volume should be drawn up?
- A0.5 mL
- B1 mL
- C2 mL✓
- D8 mL
Answer: (4 / 2) x 1 mL = 2 mL.
An adult with anaphylaxis needs adrenaline 500 micrograms IM. The ampoule is 1 mg in 1 mL (1:1,000). What volume should be given?
- A0.05 mL
- B0.5 mL✓
- C1 mL
- D5 mL
Answer: 500 micrograms = 0.5 mg. (0.5 / 1) x 1 mL = 0.5 mL. This matches the Resuscitation Council UK adult IM dose.
1 litre of fluid is to be given over 12 hours by volumetric pump. What rate should the pump be set to, to the nearest whole number?
- A83 mL/hour✓
- B120 mL/hour
- C125 mL/hour
- D167 mL/hour
Answer: 1 litre = 1,000 mL. 1,000 / 12 = 83.3, which rounds to 83 mL/hour.
250 mL of an antibiotic infusion is to run over 30 minutes by volumetric pump. What rate in mL/hour is needed?
- A125 mL/hour
- B250 mL/hour
- C375 mL/hour
- D500 mL/hour✓
Answer: 30 minutes is half an hour, so the hourly rate is 250 mL x 2 = 500 mL/hour.
1,000 mL is to be infused over 10 hours using a gravity giving set that delivers 20 drops per mL. What is the rate in drops per minute, to the nearest whole number?
- A17 drops/min
- B33 drops/min✓
- C50 drops/min
- D100 drops/min
Answer: Drops per minute = (volume x drop factor) / time in minutes = (1,000 x 20) / 600 = 33.3, which rounds to 33 drops/min.
500 mL of blood is to be transfused over 3 hours with a giving set that delivers 15 drops per mL. What is the rate in drops per minute, to the nearest whole number?
- A21 drops/min
- B28 drops/min
- C42 drops/min✓
- D63 drops/min
Answer: (500 x 15) / 180 minutes = 7,500 / 180 = 41.7, which rounds to 42 drops/min.
A 500 mL bag of fluid is running at 125 mL/hour. How long will it take to finish?
- A2 hours 30 minutes
- B3 hours
- C3 hours 30 minutes
- D4 hours✓
Answer: Time = volume / rate = 500 / 125 = 4 hours.
An infusion contains 2 mg of a drug per mL. The prescription is 10 mg per hour. What rate should the pump be set to?
- A5 mL/hour✓
- B8 mL/hour
- C12 mL/hour
- D20 mL/hour
Answer: Rate = dose per hour / concentration = 10 mg / 2 mg per mL = 5 mL/hour.
Over 24 hours a patient's total intake is 2,350 mL and total output is 1,900 mL. What is the fluid balance?
- ANegative 450 mL
- BPositive 350 mL
- CPositive 450 mL✓
- DPositive 4,250 mL
Answer: Fluid balance = intake - output = 2,350 - 1,900 = +450 mL, a positive balance.
A patient receives 1,000 mL IV and drinks 800 mL. They pass 1,500 mL of urine and vomit 250 mL. What is the fluid balance?
- ANegative 50 mL
- BPositive 50 mL✓
- CPositive 250 mL
- DPositive 1,050 mL
Answer: Intake = 1,000 + 800 = 1,800 mL. Output = 1,500 + 250 = 1,750 mL. Balance = 1,800 - 1,750 = +50 mL.
How many grams of glucose are in 500 mL of 5% glucose solution?
- A2.5 g
- B5 g
- C25 g✓
- D50 g
Answer: 5% w/v means 5 g in 100 mL. 500 mL is 5 x 100 mL, so 5 g x 5 = 25 g.
How many grams of sodium chloride are in 1 litre of 0.9% sodium chloride?
- A0.09 g
- B0.9 g
- C9 g✓
- D90 g
Answer: 0.9% w/v means 0.9 g per 100 mL. 1 litre is 10 x 100 mL, so 0.9 g x 10 = 9 g.
You need to draw up 0.4 mL of an injection. Which syringe gives the most accurate measurement?
- A1 mL syringe✓
- B2 mL syringe
- C5 mL syringe
- D10 mL syringe
Answer: Use the smallest syringe that will hold the volume, because its finer graduations allow the most accurate measurement.
An adult weighing 70 kg has had paracetamol 1 g at 06:00, 12:00 and 18:00. What is the most they can have before 06:00 the next day?
- A0.5 g
- B1 g✓
- C2 g
- D4 g
Answer: The usual maximum for adults weighing 50 kg or more is 4 g in 24 hours. 3 g has been given, so no more than 1 g can be given before 06:00, at least 4 hours after the last dose.
A vial contains 1 g of powder. Adding 4.6 mL of water gives a total volume of 5 mL. What volume contains 600 mg?
- A2.4 mL
- B2.76 mL
- C3 mL✓
- D3.3 mL
Answer: After reconstitution the concentration is 1,000 mg in 5 mL. (600 / 1,000) x 5 mL = 3 mL. The displacement value means the total volume, not the water added, must be used.
A child weighing 14 kg is prescribed ibuprofen 5 mg/kg. The suspension contains 100 mg in 5 mL. What volume should be given?
- A0.7 mL
- B1.4 mL
- C1.75 mL
- D3.5 mL✓
Answer: Dose = 5 mg x 14 kg = 70 mg. Volume = (70 / 100) x 5 mL = 3.5 mL.