1.Easy
Practice exercise (made-up values, not clinical guidance). 250 g of dextrose is dissolved in water to a total volume of 1000 mL. What is the percentage strength p (% w/v)?
250 g1000 mL
p = %
Pharmacy calculations worksheet with answers
2.Easy
Practice exercise (made-up values, not clinical guidance). A solution of epinephrine has a ratio strength of 1:1 000. How many milligrams m are in 0.3 mL?
1:1 0000.3 mL
m = mg
3.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 750 000 units. What volume V do you draw up? Round to one decimal place.
8.2 mL → 500 000 units/mL750 000 units
V = mL
4.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
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 500 mg of powder. You add 1.6 mL of diluent, and the powder adds 0.4 mL of volume. The prescription is 125 mg. Draw up the dose: what volume V do you give?
500 mg1.6 mL + 0.4 mL125 mg
V = mL
Answer key
- 1. p = 25 %
- 2. m = 0.3 mg
- 3. V = 1.5 mL
- 4. V = 5.4 mL
- 5. m = 180 g
- 6. V = 0.5 mL
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