1.Easy
A solution is 0.5% w/v. You need 15 mg of the drug. Draw up the volume in the syringe: what volume V is that?
0.5% w/v15 mg
V = mL
Pharmacy calculations worksheet with answers
2.Easy
Practice exercise (made-up values, not clinical guidance). How many g of sodium bicarbonate are in 50 mL of 8.4% w/v solution? Find m.
8.4% w/v50 mL
m = g
3.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 300 000 units. What volume V do you draw up? Round to one decimal place.
18.2 mL → 250 000 units/mL300 000 units
V = mL
4.Medium
A solution has a ratio strength of 1:10 000. You need 0.58 mg. Draw up the volume in the 10 mL syringe: what volume V is that?
1:10 0000.58 mg
V = mL
5.Hard
Practice exercise (made-up values, not clinical guidance). You must prepare 250 mL of 2% chlorhexidine from a 20% stock and purified water. How many mL V of water do you need? Round to the nearest whole mL.
20%0%2%250 mL
V = mL
6.Hard
Practice exercise (made-up values, not clinical guidance). You have 100 g of 10% salicylic acid ointment. How many grams m of 2% salicylic acid ointment must you add to make a 3% ointment? Round to the nearest whole gram.
100 g · 10%2%3%
m = g
Answer key
- 1. V = 3 mL
- 2. m = 4.2 g
- 3. V = 1.2 mL
- 4. V = 5.8 mL
- 5. V = 225 mL
- 6. m = 700 g
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