1.Easy
A solution is 1% w/v. You need 20 mg of the drug. Draw up the volume in the syringe: what volume V is that?
1% w/v20 mg
V = mL
Pharmacy calculations worksheet with answers
2.Easy
A solution is 5% w/v. You need 110 mg of the drug. Draw up the volume in the syringe: what volume V is that?
5% w/v110 mg
V = mL
3.Medium
Practice exercise (made-up values, not clinical guidance). A vial contains ceftriaxone 1000 mg as a powder. The practice label says to add 9.6 mL of sterile water; the powder adds 0.4 mL to the volume. The prescribed dose is 600 mg. What volume V do you draw up? Round to one decimal place.
1000 mg9.6 mL+0.4 mL600 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 3.2 mL of diluent. The prescribed dose is 2 000 000 units. What volume V do you draw up? Round to one decimal place.
3.2 mL → 1 000 000 units/mL2 000 000 units
V = mL
5.Hard
Practice exercise (made-up values, not clinical guidance). You have 20 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.
20 g · 10%2%3%
m = g
6.Hard
Practice exercise (made-up values, not clinical guidance). You must prepare 500 mL of 8% sodium chloride by mixing 23% and 3% sodium chloride. How many mL V of the 23% solution do you need? Round to the nearest whole mL.
23%3%8%500 mL
V = mL
Answer key
- 1. V = 2 mL
- 2. V = 2.2 mL
- 3. V = 6 mL
- 4. V = 2 mL
- 5. m = 140 g
- 6. V = 125 mL
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