NMC CBT Part A numeracy guide
The question types, the formulas, and how to avoid losing marks.
Part A has 15 questions in 30 minutes, and you need 13 correct to pass. The questions are applied drug calculations of the kind nurses use every day. The NMC's test specification sets out how many questions of each type appear:
| Content area | Questions |
|---|---|
| Measuring the correct dose | 2 |
| Metric units | 2 |
| Oral medications | 4 |
| Injections | 3 |
| Intravenous infusions | 3 |
| Fluid balance | 1 |
| Total | 15 |
The formulas you need
| Calculation | Formula |
|---|---|
| Tablets, liquids and injections | (What you want ÷ what you have) × volume |
| Weight-based dose | Dose per kg × weight in kg |
| Infusion pump rate | Volume (ml) ÷ time (hours) = ml/hr |
| Gravity drip rate | (Volume (ml) × drop factor) ÷ time (minutes) = drops/min |
| Fluid balance | Total intake − total output |
| Units | 1 g = 1000 mg; 1 mg = 1000 micrograms; 1 L = 1000 ml |
Avoiding common mistakes
- Convert everything to the same unit before you calculate.
- Round only at the end, and only to the precision the question asks for.
- Drip rates are whole drops, so round to the nearest whole number.
- Sense-check the answer. Ten tablets or 50 ml for one IM injection is almost certainly wrong.
- Write each step on the note board, so you can check it quickly.
Practise every type with worked answers in drug calculations, then sit a timed Part A in the mock exam, which follows the same mix of question types.
How many numeracy questions can I get wrong in the NMC CBT?
Two. The current Part A pass mark is 87%, which is 13 out of 15 correct, so accuracy matters more than speed. The NMC suggests spending no more than 2 minutes on each question, which leaves time to check your working.
Are NMC CBT numeracy questions multiple choice?
No. Part A answers are short numerical answers that you type in. The NMC notes it may also be necessary to give the correct unit, so read each question carefully for the unit and the rounding it asks for.
What is the formula for drip rate?
Drops per minute = (volume in ml × drop factor in drops per ml) ÷ time in minutes. Standard giving sets for clear fluids are commonly 20 drops per ml, and blood giving sets 15 drops per ml, but always use the drop factor stated in the question.
Put this into practice with free questions and timed mock exams.
Start practising