1.Easy
A solution is 5% w/v. You need 45 mg of the drug. Draw up the volume in the syringe: what volume V is that?
5% w/v45 mg
V = mL
Pharmacy calculations worksheet with answers
2.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
3.Medium
A solution has a ratio strength of 1:10 000. You need 0.54 mg. Draw up the volume in the 10 mL syringe: what volume V is that?
1:10 0000.54 mg
V = mL
4.Medium
Practice exercise (made-up values, not clinical guidance). A vial contains cefuroxime 750 mg as a powder. The practice label says to add 7.2 mL of sterile water; the powder adds 0.3 mL to the volume. What is the concentration C in mg/mL after reconstitution?
750 mg7.2 mL+0.3 mL
C = mg/mL
5.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 6% ointment? Round to the nearest whole gram.
100 g · 10%2%6%
m = g
6.Hard
Practice exercise (made-up values, not clinical guidance). You must prepare 600 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%600 mL
V = mL
Answer key
- 1. V = 0.9 mL
- 2. V = 2 mL
- 3. V = 5.4 mL
- 4. C = 100 mg/mL
- 5. m = 100 g
- 6. V = 540 mL
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