CBT Numeracy: 10 Worked Examples for the NMC Test

Ten worked CBT-style numeracy examples. Each one tests one of the methods from Chapter 72. Work through with paper and a calculator before reading the answer.

The values are illustrative. Real CBT questions use the same calculation methods with different scenarios and numbers.

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Example 1: Tablet calculation

A patient is prescribed 75 mg of a medication. Available: 25 mg tablets.

How many tablets are needed?

A. 2 tablets B. 3 tablets C. 4 tablets D. 1.5 tablets

Answer: B (3 tablets).

75 ÷ 25 = 3 tablets.

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Example 2: Liquid oral medication

A patient is prescribed 400 mg of an antibiotic syrup. Available: 250 mg in 5 mL.

What volume should be administered?

A. 5 mL B. 6 mL C. 8 mL D. 10 mL

Answer: C (8 mL).

(400 ÷ 250) × 5 = 1.6 × 5 = 8 mL.

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Example 3: IV drip rate

A patient requires 500 mL of 0.9% sodium chloride to run over 5 hours, using a standard giving set delivering 20 drops/mL.

What is the drip rate in drops per minute?

A. 12 drops/min B. 17 drops/min C. 33 drops/min D. 100 drops/min

Answer: C (33 drops/min).

Time in minutes: 5 × 60 = 300. Drops per minute: (500 × 20) ÷ 300 = 10,000 ÷ 300 = 33.3 ≈ 33.

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Example 4: IV infusion rate (pump)

A patient requires 1,000 mL of intravenous fluid over 8 hours via an infusion pump.

What rate should the pump be set to?

A. 100 mL/hour B. 125 mL/hour C. 150 mL/hour D. 200 mL/hour

Answer: B (125 mL/hour).

1,000 ÷ 8 = 125 mL/hour.

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Example 5: Weight-based dosing

A child weighing 18 kg is prescribed a medication at 2.5 mg/kg.

What total dose is required?

A. 25 mg B. 30 mg C. 45 mg D. 50 mg

Answer: C (45 mg).

2.5 × 18 = 45 mg.

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Example 6: Unit conversion plus tablet calculation

A prescription reads “0.5 g of metronidazole.” Tablets available are 250 mg.

How many tablets should be administered?

A. 1 tablet B. 2 tablets C. 3 tablets D. 5 tablets

Answer: B (2 tablets).

Convert: 0.5 g = 500 mg. 500 ÷ 250 = 2 tablets.

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Example 7: Continuous infusion rate

A patient requires a heparin infusion of 1,200 units per hour. Available solution: 25,000 units in 500 mL.

What pump rate should be set in mL/hour?

A. 12 mL/hour B. 18 mL/hour C. 24 mL/hour D. 30 mL/hour

Answer: C (24 mL/hour).

(1,200 × 500) ÷ 25,000 = 600,000 ÷ 25,000 = 24 mL/hour.

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Example 8: Fluid balance

A patient’s 24-hour intake was 2,200 mL (oral 1,400 mL, IV 800 mL). Output was 1,800 mL urine, 100 mL nasogastric drain, 700 mL insensible losses (estimated).

What is the 24-hour fluid balance?

A. −400 mL B. +400 mL C. −600 mL D. +600 mL

Answer: A (−400 mL).

Total in = 2,200. Total out = 1,800 + 100 + 700 = 2,600. Balance = 2,200 − 2,600 = −400 mL (negative balance).

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Example 9: BMI

A patient weighs 85 kg and is 1.70 m tall.

What is their BMI? (To one decimal place.)

A. 25.0 B. 27.4 C. 29.4 D. 32.0

Answer: C (29.4).

1.70² = 2.89. 85 ÷ 2.89 = 29.4.

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Example 10: Mixed conversion and infusion

A patient needs a dose of 250 micrograms of digoxin orally. The bottle is labelled 50 mcg/mL.

What volume should be given?

A. 2 mL B. 3 mL C. 4 mL D. 5 mL

Answer: D (5 mL).

250 ÷ 50 = 5. Volume: 5 mL.

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Patterns across the 10 examples

Three habits to take from this set:

1. Convert first, then calculate. Examples 6 and 10 both had unit conversions that, if skipped, produced answers in the wrong unit.

2. Sanity-check the magnitude. A heparin infusion at 240 mL/hour (Example 7 if you missed a decimal place) is implausible. It would empty the bag in 2 hours, which would also empty the patient. The realistic answer was 24 mL/hour.

3. Use the answer options as a check. If your calculated answer doesn’t match any of the four options, you’ve made an arithmetic error somewhere. The CBT options are designed so wrong answers reflect common errors. If you’ve matched a wrong option, you’ve made a known error.

The next chapter covers the clinical section of the CBT: the 105+ questions across the 7 Future Nurse Platforms.