1.Easy
Practice exercise (made-up values, not clinical guidance). A solution of potassium permanganate has a ratio strength of 1:10 000. How many milligrams m are in 500 mL?
1:10 000500 mL
m = mg
Pharmacy calculations worksheet with answers
2.Easy
A solution is 1% w/v. You need 26 mg of the drug. Draw up the volume in the syringe: what volume V is that?
1% w/v26 mg
V = mL
3.Medium
A solution has a ratio strength of 1:10 000. You need 0.16 mg. Draw up the volume in the 10 mL syringe: what volume V is that?
1:10 0000.16 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 600 000 units. What volume V do you draw up? Round to one decimal place.
3.2 mL → 1 000 000 units/mL600 000 units
V = mL
5.Hard
A vial holds 250 mg of powder. You add 1.9 mL of diluent, and the powder adds 0.6 mL of volume. The prescription is 100 mg. Draw up the dose: what volume V do you give?
250 mg1.9 mL + 0.6 mL100 mg
V = mL
6.Hard
Practice exercise (made-up values, not clinical guidance). You must prepare 750 mL of 40% dextrose by mixing 70% and 10% dextrose. How many mL V of the 10% solution do you need? Round to the nearest whole mL.
70%10%40%750 mL
V = mL
Answer key
- 1. m = 50 mg
- 2. V = 2.6 mL
- 3. V = 1.6 mL
- 4. V = 0.6 mL
- 5. V = 1 mL
- 6. V = 375 mL
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