Part 1 (Numeracy) of the NMC CBT consists of 15 questions. To pass, you must achieve a score of 87% (answering at least 13 out of 15 questions correctly). Every single calculation is critical to your success, so minor rounding or formula errors must be avoided. To help you conquer clinical math, here are 5 real-world dosage calculation examples using the exact formatting and style you will face in the Pearson VUE center, followed by a list of common traps and FAQs.
Example 1: Liquid Dose Calculation
The Question: A patient is prescribed 375mg of Liquid Paracetamol. The stock bottle contains Paracetamol at a strength of 250mg per 5mL. What volume in mL should be administered?
The Formula: (Prescribed Dose / Stock Strength) × Stock Volume = Volume to Administer
The Calculation:
- Identify parameters: Want = 375mg, Have = 250mg, Volume = 5mL.
- Apply the formula:
(375 / 250) × 5 - Simplify:
1.5 × 5 = 7.5
The Correct Answer: 7.5 mL
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Test Your Numeracy Score Free →Example 2: IV Drip Rate Calculation (Drops/Minute)
The Question: Administer 1,000 mL of 0.9% Normal Saline over 8 hours. The giving set has a drop factor of 20 drops/mL. What is the correct drip rate in drops per minute (dpm)? (Round to the nearest whole number).
The Formula: (Total Volume in mL × Drop Factor) / Total Time in Minutes = Drops per Minute
The Calculation:
- Convert hours to minutes:
8 hours × 60 minutes = 480 minutes. - Apply parameters to the formula:
(1000 × 20) / 480 - Calculate:
20,000 / 480 = 41.666... - Round to the nearest whole number as specified:
42
The Correct Answer: 42 drops/min (or simply 42)
Example 3: Pediatric Weight-Based Dosing
The Question: A child weighing 14 kg is prescribed Erythromycin at 12.5 mg/kg per dose. The suspension available is 250 mg in 5 mL. What volume in mL should you administer for one single dose?
The Formula: Step 1: Calculate total dose in mg: Weight (kg) × Dose per kg. Step 2: Use the liquid dose formula.
The Calculation:
- Calculate mg dose:
14 kg × 12.5 mg/kg = 175 mg. - Apply parameters: Want = 175mg, Have = 250mg, Volume = 5mL.
- Apply formula:
(175 / 250) × 5 - Simplify:
0.7 × 5 = 3.5
The Correct Answer: 3.5 mL
Example 4: IV Infusion Rate Calculation (mL/Hour)
The Question: A patient is prescribed 500 mL of 5% Dextrose to run over 4 hours. At what rate in mL per hour should the volumetric pump be set?
The Formula: Total Volume in mL / Total Time in Hours = Rate in mL/hour
The Calculation:
- Identify parameters: Volume = 500 mL, Time = 4 hours.
- Apply formula:
500 / 4 = 125
The Correct Answer: 125 mL/hour (or simply 125)
Example 5: Complex Weight-Based Infusion Rate
The Question: A patient weighing 70 kg is prescribed a medication to run at 2 mcg/kg/minute. The concentration is 100 mg of the medication in 50 mL of Normal Saline. What is the hourly infusion rate in mL/hour? (Round to one decimal place).
The Calculation:
- Calculate mcg per minute:
70 kg × 2 mcg/kg/min = 140 mcg/min. - Calculate mcg per hour:
140 mcg/min × 60 minutes = 8,400 mcg/hour. - Convert mcg/hour to mg/hour:
8,400 mcg / 1000 = 8.4 mg/hour. - Calculate mL per hour using the concentration:
(8.4 mg / 100 mg) × 50 mL = 4.2 mL/hour.
The Correct Answer: 4.2 mL/hour (or 4.2)
6. Common Numeracy Pitfalls & Traps
- Incorrect Rounding: Standard Pearson VUE guidelines specify when to round to the nearest whole number (e.g. drip rates) versus decimal places. Rounding early in multi-step equations will distort your final number. Only round your final answer.
- Unit Mismatches: Mixing milligrams (mg) and micrograms (mcg) is a classic trap. Always convert units to match before running your equations (e.g., 1 mg = 1,000 mcg).
- Time Units: Double-check if a rate is specified per minute or per hour. Volume pumps are set in mL/hour, whereas giving sets measure drops/minute.
7. Frequently Asked Questions (FAQ)
Q: Am I allowed to use a physical calculator on the exam?
A: No. You cannot bring your own calculator. The Pearson VUE system provides a built-in on-screen calculator that you must operate with your mouse. Practice using an on-screen calculator before the test to get comfortable with the interface.
Q: What happens if I make a minor rounding error on a math question?
A: The system marks mathematically incorrect inputs as incorrect. Because numeracy questions require absolute accuracy (safety-critical), a single incorrect value will fail you for the numeracy part of the exam.
Q: Do I need to write the units (like 'mL' or 'drops/min') in the input box?
A: Read the question prompt carefully. Often, the units are already written next to the input field, and you only need to type the numerical digits. Adding units when not requested can result in the answer being marked wrong.
Master the Remaining Math Formulas
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