1.Easy
Practice exercise (made-up values, not clinical guidance). How many mg of lidocaine are in 20 mL of 1% w/v solution? Find m.
1% w/v20 mL
m = mg
Pharmacy calculations worksheet with answers
2.Easy
A solution is 2% w/v. You need 86 mg of the drug. Draw up the volume in the syringe: what volume V is that?
2% w/v86 mg
V = mL
3.Medium
A solution has a ratio strength of 1:10 000. You need 0.1 mg. Draw up the volume in the 10 mL syringe: what volume V is that?
1:10 0000.1 mg
V = mL
4.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 500 mg. What volume V do you draw up? Round to one decimal place.
1000 mg9.6 mL+0.4 mL500 mg
V = 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 3% ointment? Round to the nearest whole gram.
100 g · 10%2%3%
m = g
6.Hard
A vial holds 1000 mg of powder. You add 4.4 mL of diluent, and the powder adds 0.6 mL of volume. The prescription is 920 mg. Draw up the dose: what volume V do you give?
1000 mg4.4 mL + 0.6 mL920 mg
V = mL
Answer key
- 1. m = 200 mg
- 2. V = 4.3 mL
- 3. V = 1 mL
- 4. V = 5 mL
- 5. m = 700 g
- 6. V = 4.6 mL
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