1.Easy
Practice exercise (made-up values, not clinical guidance). A solution of potassium permanganate has a ratio strength of 1:5 000. How many milligrams m are in 250 mL?
1:5 000250 mL
m = mg
Pharmacy calculations worksheet with answers
2.Easy
Practice exercise (made-up values, not clinical guidance). How many g of dextrose are in 20 mL of 50% w/v solution? Find m.
50% w/v20 mL
m = g
3.Medium
A solution has a ratio strength of 1:10 000. You need 0.5 mg. Draw up the volume in the 10 mL syringe: what volume V is that?
1:10 0000.5 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 18.2 mL of diluent. The prescribed dose is 600 000 units. What volume V do you draw up? Round to one decimal place.
18.2 mL → 250 000 units/mL600 000 units
V = mL
5.Hard
Practice exercise (made-up values, not clinical guidance). You have 50 g of 5% coal tar ointment. How many grams m of 1% coal tar ointment must you add to make a 2% ointment? Round to the nearest whole gram.
50 g · 5%1%2%
m = g
6.Hard
Practice exercise (made-up values, not clinical guidance). You must prepare 250 mL of 45% ethanol from a 90% stock and purified water. How many mL V of water do you need? Round to the nearest whole mL.
90%0%45%250 mL
V = mL
Answer key
- 1. m = 50 mg
- 2. m = 10 g
- 3. V = 5 mL
- 4. V = 2.4 mL
- 5. m = 150 g
- 6. V = 125 mL
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