Pharmacy calculations practice questions

Written by the Quizard team. Last updated 3 November 2026

Calculations are usually lost to units and rushing, not hard maths. Write the units on every line and estimate the answer before you work it out. Your school may set its own rounding rules, so check those before an exam.

1. 1. A 70 kg patient is prescribed 5 mg/kg. What is the dose?

   • 140 mg
   • 210 mg
   • 280 mg
   • 350 mg
   Show answer

   Answer: 350 mg. 5 mg/kg × 70 kg = 350 mg.

2. 2. One liter of IV fluid is ordered over 8 hours. What is the rate?

   • 125 mL/h
   • 150 mL/h
   • 200 mL/h
   • 250 mL/h
   Show answer

   Answer: 125 mL/h. 1,000 mL ÷ 8 h = 125 mL/h.

3. 3. One liter runs over 8 hours through a 15 gtt/mL set. What is the drip rate, to the nearest drop?

   • 21 gtt/min
   • 31 gtt/min
   • 42 gtt/min
   • 125 gtt/min
   Show answer

   Answer: 31 gtt/min. 1,000 × 15 ÷ 480 minutes = 31.25, which rounds to 31 gtt/min.

4. 4. How many grams of sodium chloride are in 500 mL of 0.9% w/v solution?

   • 4.5 g
   • 9 g
   • 18 g
   • 45 g
   Show answer

   Answer: 4.5 g. 0.9 g per 100 mL × 5 = 4.5 g.

5. 5. What is the concentration of a 1:1000 epinephrine solution?

   • 0.1 mg/mL
   • 1 mg/mL
   • 10 mg/mL
   • 100 mg/mL
   Show answer

   Answer: 1 mg/mL. 1 g in 1,000 mL equals 1,000 mg in 1,000 mL, which is 1 mg/mL.

6. 6. How much 10% stock is needed to make 500 mL of a 2% solution?

   • 50 mL
   • 100 mL
   • 200 mL
   • 250 mL
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   Answer: 100 mL. C1V1 = C2V2, so 10 × V1 = 2 × 500, and V1 = 100 mL.

7. 7. To make 150 g of a 10% ointment from 20% and 5% ointments, how much 20% do you need?

   • 25 g
   • 50 g
   • 75 g
   • 100 g
   Show answer

   Answer: 50 g. Alligation gives 5 parts of 20% to 10 parts of 5%, a 1:2 ratio. One third of 150 g is 50 g. Check: 10 g + 5 g = 15 g of drug in 150 g.

8. 8. About how many mEq of potassium are in 1.5 g of KCl (MW 74.5)?

   • 5 mEq
   • 10 mEq
   • 15 mEq
   • 20 mEq
   Show answer

   Answer: 20 mEq. 1,500 mg ÷ 74.5 × 1 = 20.1, so about 20 mEq.

9. 9. Estimate CrCl by Cockcroft-Gault: male, 60 years, 70 kg, serum creatinine 1.0 mg/dL.

   • About 58 mL/min
   • About 66 mL/min
   • About 78 mL/min
   • About 98 mL/min
   Show answer

   Answer: About 78 mL/min. (140 − 60) × 70 ÷ (72 × 1.0) = 77.8 mL/min.

10. 10. Using Mosteller, a patient is 170 cm and 70 kg. What is a 100 mg/m² dose, to the nearest mg?

    • 170 mg
    • 182 mg
    • 200 mg
    • 238 mg
    Show answer

    Answer: 182 mg. BSA = √(170 × 70 ÷ 3600) = 1.82 m². 1.82 × 100 = 182 mg.

11. 11. A 20 kg child needs amoxicillin 40 mg/kg/day in 2 divided doses. How many mL per dose of 250 mg/5 mL?

    • 4 mL
    • 8 mL
    • 10 mL
    • 16 mL
    Show answer

    Answer: 8 mL. 40 × 20 = 800 mg/day, so 400 mg per dose. 400 ÷ 50 mg/mL = 8 mL.

12. 12. A patient takes 1.5 tablets three times a day. How many days do 90 tablets last?

    • 5 days
    • 10 days
    • 15 days
    • 20 days
    Show answer

    Answer: 20 days. 1.5 × 3 = 4.5 tablets a day, and 90 ÷ 4.5 = 20 days.

13. 13. What ratio strength is the same as 0.05% w/v?

    • 1:200
    • 1:500
    • 1:2000
    • 1:5000
    Show answer

    Answer: 1:2000. 0.05 g in 100 mL is 1 g in 2,000 mL.

14. 14. How many mL of U-100 insulin contain 35 units?

    • 0.35 mL
    • 0.7 mL
    • 3.5 mL
    • 35 mL
    Show answer

    Answer: 0.35 mL. U-100 has 100 units/mL, and 35 ÷ 100 = 0.35 mL.

15. 15. Dopamine 5 mcg/kg/min is ordered for an 80 kg patient. The bag is 400 mg in 250 mL. What is the pump rate?

    • 5 mL/h
    • 10 mL/h
    • 15 mL/h
    • 24 mL/h
    Show answer

    Answer: 15 mL/h. 5 × 80 = 400 mcg/min, which is 24 mg/h. The bag is 1.6 mg/mL, and 24 ÷ 1.6 = 15 mL/h.

For exam study only, not clinical guidance. Doses, reference ranges and protocols vary, so follow your course, your local policy and current references. Spotted a mistake? Tell us.