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Six calculations that cover almost everything you will be asked in a numeracy assessment or on a drug page: dose by weight, volume to draw up, percentage and ratio strengths, micrograms and infusion rates. Each one is worked in full, with the error people actually make.
A 24 kg child needs a drug prescribed at 10 mg/kg. How many milligrams do you give?
Answer: 240 mg
Watch out: Check the guideline's maximum single dose before you draw up — a weight-based sum can exceed the adult cap in a large child.
You need 250 mg from a vial labelled 500 mg in 5 mL. What volume do you draw up?
Answer: 2.5 mL
Watch out: Read the label as a whole amount in a whole volume, not as 'per mL', or you will be out by the dilution factor.
How much drug is in 10 mL of a 1% solution?
Answer: 100 mg
Watch out: Percentage is always grams per 100 mL. Converting to mg/mL first turns every percentage question into a simple multiplication.
How much adrenaline is in 1 mL of 1:1,000?
Answer: 1 mg in 1 mL
Watch out: 1:10,000 is 100 micrograms per mL. Confusing the two is a ten-fold error — state the strength out loud with your crewmate before administration.
A drug is given at 2 micrograms/kg to a 70 kg adult, from a vial containing 100 micrograms in 2 mL.
Answer: 140 micrograms = 2.8 mL
Watch out: Write micrograms in full. 'mcg' handwritten as 'mg' is one of the most common medication errors reported in pre-hospital care.
1,000 mL is to run over 4 hours. What rate do you set on the pump?
Answer: 250 mL/hour
Watch out: For a gravity set, multiply mL/hour by the giving-set drop factor and divide by 60 to get drops per minute.
The pharmacology bank turns these sums into timed questions with rationales, alongside pharmacokinetics and pharmacodynamics.
Educational examples only. Always confirm doses against the current JRCALC Clinical Practice Guidelines edition and your trust's policies, and work within your scope of practice.