Pharmaceutical Calculations
25 free practice questions with explanations
PassNova has 25 free Pharmacy Technician practice questions on Pharmaceutical 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.
Pharmaceutical Calculations: example questions & answers
25 worked examples with answers and explanations below. Practise them in the browser with instant feedback on every answer.
A patient requires 500 mg of amoxicillin. The suspension contains 250 mg/5 ml. How many ml should be dispensed?
- A15 ml
- B5 ml
- C10 ml✓
- D20 ml
Answer: Using the formula: (Required dose / Available strength) × Volume = (500 / 250) × 5 = 2 × 5 = 10 ml
Convert 0.5 grams to milligrams.
- A5 mg
- B50 mg
- C500 mg✓
- D5000 mg
Answer: 1 gram = 1000 milligrams, so 0.5 g = 0.5 × 1000 = 500 mg
A child weighs 20 kg and requires a dose of 10 mg/kg of a medicine. What is the total dose required?
- A400 mg
- B200 mg✓
- C100 mg
- D50 mg
Answer: Dose = 10 mg/kg × 20 kg = 200 mg
A solution contains 2% w/v of active ingredient. How many grams are in 500 ml?
- A1 g
- B5 g
- C10 g✓
- D20 g
Answer: 2% w/v means 2 g per 100 ml. In 500 ml: (2/100) × 500 = 10 g
A pharmacy buys 100 tablets of ibuprofen 200 mg for £5.00 and sells them for £8.00. What is the percentage profit?
- A40%
- B60%✓
- C50%
- D80%
Answer: Profit = £8.00 - £5.00 = £3.00. Percentage profit = (3/5) × 100 = 60%
An infusion of 500 ml is to be given over 2 hours. What is the infusion rate in ml/hour?
- A150 ml/hr
- B250 ml/hr✓
- C200 ml/hr
- D300 ml/hr
Answer: Infusion rate = Total volume / Time (hours) = 500 ml / 2 hours = 250 ml/hr
Convert 1500 micrograms (mcg) to milligrams (mg).
- A15 mg
- B1.5 mg✓
- C150 mg
- D0.15 mg
Answer: 1000 mcg = 1 mg, so 1500 mcg = 1500 / 1000 = 1.5 mg
A patient needs 15 mg of a drug, but the available tablets contain 5 mg each. How many tablets should be given?
- A4 tablets
- B3 tablets✓
- C5 tablets
- D2 tablets
Answer: Number of tablets = Required dose / Dose per tablet = 15 mg / 5 mg = 3 tablets
A concentrated solution is diluted 1 in 4. What is the dilution factor?
- A1
- B2
- C4✓
- D8
Answer: A 1 in 4 dilution means 1 part concentrate mixed with 3 parts solvent, resulting in 4 parts total. Dilution factor = 4
A child weighs 30 pounds (lbs). Convert this to kilograms (kg). (1 kg = 2.2 lbs)
- A10.6 kg
- B13.6 kg✓
- C15.2 kg
- D20 kg
Answer: Weight in kg = Weight in lbs / 2.2 = 30 / 2.2 = 13.6 kg
A dose of 50 mg/kg is required for a 2-year-old child weighing 15 kg. The available suspension contains 100 mg/5 ml. What volume should be dispensed?
- A3.75 ml
- B15 ml
- C7.5 ml
- D37.5 ml✓
Answer: Total dose = 50 mg/kg × 15 kg = 750 mg. Using the formula (Required dose / Available strength) × Volume = (750 / 100) × 5 = 7.5 × 5 = 37.5 ml.
A batch of ointment contains 2 g of active ingredient in 50 g of base. What is the percentage w/w concentration?
- A5%
- B2%
- C4%✓
- D10%
Answer: Percentage w/w = (Active ingredient / Total weight) × 100 = (2 / 50) × 100 = 4% w/w
Convert 0.002 kilograms (kg) to milligrams (mg).
- A2 mg
- B20 mg
- C2000 mg✓
- D200 mg
Answer: 1 kg = 1,000,000 mg, so 0.002 kg = 0.002 × 1,000,000 = 2000 mg
A patient is prescribed 1.5 grams of paracetamol. Tablets available are 500 mg each. How many tablets are needed?
- A6 tablets
- B4 tablets
- C2 tablets
- D3 tablets✓
Answer: 1.5 g = 1500 mg. Number of tablets = 1500 mg / 500 mg = 3 tablets
A 10% solution of sodium chloride contains how many grams per 100 ml?
- A10 g✓
- B20 g
- C1 g
- D5 g
Answer: 10% w/v means 10 g per 100 ml, so the answer is 10 g
An IV infusion contains 500 mg of drug in 250 ml of fluid. What is the concentration in mg/ml?
- A4 mg/ml
- B1 mg/ml
- C5 mg/ml
- D2 mg/ml✓
Answer: Concentration = Total drug / Total volume = 500 mg / 250 ml = 2 mg/ml
A liquid formulation contains 25 mg/ml. A patient requires 75 mg. What volume should be measured?
- A10 ml
- B3 ml✓
- C2 ml
- D5 ml
Answer: Volume = Required dose / Concentration = 75 mg / 25 mg/ml = 3 ml
A 1 in 1000 solution of a substance means:
- A1% w/v
- B0.1% w/v✓
- C10% w/v
- D0.01% w/v
Answer: 1 in 1000 = 1 g in 1000 ml = 0.1% w/v
A patient requires 0.25 mg of a medicine. The available liquid contains 0.05 mg/ml. What volume is needed?
- A20 ml
- B2.5 ml
- C10 ml
- D5 ml✓
Answer: Volume = 0.25 mg / 0.05 mg/ml = 5 ml
A cream contains 5% hydrocortisone. How much active ingredient is in a 30 g tube?
- A0.15 g
- B1.5 g✓
- C5 g
- D0.5 g
Answer: Amount = (Percentage / 100) × Total weight = (5 / 100) × 30 = 1.5 g
An infant weighs 4 kg. The recommended dose is 5 mg/kg/day. The medicine is available as 20 mg/5 ml suspension. How many ml per dose if given twice daily?
- A2.5 ml✓
- B5 ml
- C20 ml
- D10 ml
Answer: Daily dose = 5 mg/kg × 4 kg = 20 mg. Per dose (twice daily) = 20 / 2 = 10 mg. Volume = (10 / 20) × 5 = 2.5 ml
Convert 1.8 metres to centimetres (cm).
- A180 cm✓
- B18 cm
- C100 cm
- D1800 cm
Answer: 1 metre = 100 cm, so 1.8 m = 1.8 × 100 = 180 cm
A patient is prescribed 1 mg of digoxin. The tablets contain 500 micrograms each. How many tablets should be dispensed?
- A1 tablet
- B4 tablets
- C2 tablets✓
- D5 tablets
Answer: 1 mg = 1000 mcg. Number of tablets = 1000 mcg / 500 mcg = 2 tablets
A medicine needs to be mixed at a ratio of 1:4 (medicine to diluent). If you start with 100 ml of medicine, how much diluent is needed?
- A100 ml
- B400 ml✓
- C200 ml
- D300 ml
Answer: Ratio 1:4 means 1 part medicine to 4 parts diluent. If 100 ml medicine, then 100 × 4 = 400 ml diluent
A controlled drug prescription is for 30 tablets to last 1 month. What is the daily dose if each tablet is 10 mg?
- A10 mg✓
- B5 mg
- C20 mg
- D15 mg
Answer: 30 tablets over 30 days = 1 tablet per day = 10 mg daily