1.Easy
A solution is 5% w/v. You need 155 mg of the drug. Draw up the volume in the syringe: what volume V is that?
5% w/v155 mg
V = mL
Pharmacy calculations worksheet with answers
2.Easy
A solution is 5% w/v. You need 195 mg of the drug. Draw up the volume in the syringe: what volume V is that?
5% w/v195 mg
V = mL
3.Medium
A solution has a ratio strength of 1:1000. You need 0.81 mg. Draw up the volume in the 1 mL syringe: what volume V is that?
1:10000.81 mg
V = mL
4.Medium
Practice exercise (made-up values, not clinical guidance). A vial of penicillin G contains 5 000 000 units. Its practice label gives three strengths (see the table). You add 18.2 mL of diluent. The prescribed dose is 800 000 units. What volume V do you draw up? Round to one decimal place.
18.2 mL → 250 000 units/mL800 000 units
V = mL
5.Hard
Practice exercise (made-up values, not clinical guidance). You have 30 g of 10% salicylic acid ointment. How many grams m of 2% salicylic acid ointment must you add to make a 5% ointment? Round to the nearest whole gram.
30 g · 10%2%5%
m = g
6.Hard
Practice exercise (made-up values, not clinical guidance). You must prepare 200 mL of 3% hydrogen peroxide from a 30% stock and purified water. How many mL V of water do you need? Round to the nearest whole mL.
30%0%3%200 mL
V = mL
Answer key
- 1. V = 3.1 mL
- 2. V = 3.9 mL
- 3. V = 0.81 mL
- 4. V = 3.2 mL
- 5. m = 50 g
- 6. V = 180 mL
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