1.Easy
A solution is 1% w/v. You need 13 mg of the drug. Draw up the volume in the syringe: what volume V is that?
1% w/v13 mg
V = mL
Pharmacy calculations worksheet with answers
2.Easy
A solution is 0.5% w/v. You need 10 mg of the drug. Draw up the volume in the syringe: what volume V is that?
0.5% w/v10 mg
V = mL
3.Medium
A solution has a ratio strength of 1:10 000. You need 0.68 mg. Draw up the volume in the 10 mL syringe: what volume V is that?
1:10 0000.68 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 8.2 mL of diluent. The prescribed dose is 1 200 000 units. What volume V do you draw up? Round to one decimal place.
8.2 mL → 500 000 units/mL1 200 000 units
V = mL
5.Hard
Practice exercise (made-up values, not clinical guidance). You have 60 g of 10% salicylic acid ointment. How many grams m of 2% salicylic acid ointment must you add to make a 4% ointment? Round to the nearest whole gram.
60 g · 10%2%4%
m = g
6.Hard
A vial holds 1000 mg of powder. You add 2.3 mL of diluent, and the powder adds 0.2 mL of volume. The prescription is 320 mg. Draw up the dose: what volume V do you give?
1000 mg2.3 mL + 0.2 mL320 mg
V = mL
Answer key
- 1. V = 1.3 mL
- 2. V = 2 mL
- 3. V = 6.8 mL
- 4. V = 2.4 mL
- 5. m = 180 g
- 6. V = 0.8 mL
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