Pharmacy calculations drill
Fresh calculation questions in the style of the NAPLEX, one at a time. Work each one by hand, type your answer, and see the full working. No account.
Work it out on paper with a basic calculator, as on exam day, and check.
Creatinine clearance calculator
Cockcroft-Gault from age, weight and serum creatinine, with ideal body weight if you add a height.
Creatinine clearance, actual weight
42 mL/min
Cockcroft-Gault: (140 - age) x weight / (72 x SCr), x 0.85 for women
IV infusion rate calculator
Pump rate
15 mL/hour
Bag strength 1.6 mg/mL
Alligation and dilution calculator
Of the 10%
10
and 50 of the 1%
The formulas
| Calculation | Formula |
|---|---|
| Ideal body weight (Devine) | Men 50 kg, women 45.5 kg, + 2.3 kg per inch over 5 feet |
| Creatinine clearance (Cockcroft-Gault) | (140 - age) x weight / (72 x SCr), x 0.85 for women |
| Body surface area (Mosteller) | Square root of (height cm x weight kg / 3600) |
| Infusion rate | mg/hour / (mg/mL) = mL/hour |
| Drip rate | mL x drop factor / minutes |
| Dilution | C1 x V1 = C2 x V2 |
| Milliequivalents | mg x valence / molecular weight |
| Loading dose | Target concentration x Vd / (S x F) |
| Number needed to treat | 1 / absolute risk reduction, rounded up |
Then the whole exam
The free diagnostic has 15 questions across all six areas, led by calculations, and takes 24 minutes. No account. You get your score in each area and a short lesson on the one to fix first.
Questions people ask
How many calculation questions are on the NAPLEX?
NABP does not publish a count. Pharmaceutical calculations are a named part of Area 1, Foundational Knowledge, which is 25% of the exam, and calculations also appear inside patient cases.
Can you use a calculator on the NAPLEX?
Yes, an on-screen calculator with scientific and 5-function modes. You cannot bring your own.
Which weight goes into Cockcroft-Gault?
A question will usually say. This drill states the weight to use in every stem, and the calculator shows both the actual-weight result and the result with the lower of ideal and actual weight.
How do you round the number needed to treat?
Up, to the next whole patient: an NNT of 26.3 becomes 27.