A patient is prescribed 0.25 g of a drug. Available tablets are 125 mg each. How many tablets will you administer?

Appeared in: NORCET 10 Prelims-2026

Explanation

The first step in medication calculation is to ensure both the prescribed dose and the available dose are in the same unit of measurement.
The prescribed dose must be converted from grams (g) to milligrams (mg). Since 1 g equals 1000 mg, 0.25 g is equivalent to 250 mg (0.25 x 1000).
The standard formula for calculating tablets is: (Dose to be administered / Dose available per tablet) = Number of tablets.
Applying the formula with the converted values: (250 mg / 125 mg) results in 2. Therefore, 2 tablets should be administered.

Option B: Administering 3 tablets would result in a total dose of 375 mg (3 tablets × 125 mg/tablet), which is a significant overdose compared to the prescribed 250 mg.
Option C: Administering 0.5 (half) a tablet would provide only 62.5 mg (0.5 tablets × 125 mg/tablet), which is a significant underdose of the prescribed 250 mg.
Option D: Administering 6 tablets would result in a dose of 750 mg (6 tablets × 125 mg/tablet). This is three times the prescribed amount and constitutes a dangerous overdose.

Visual 1: Infographic - A simple chart showing the conversion between grams (g), milligrams (mg), and micrograms (mcg) to reinforce the metric system relationships.
Visual 2: Diagram - Illustrating the medication calculation formula: (Dose Ordered / Dose on Hand) x Quantity = Amount to Administer.

Clinical Relevance

Nursing practice connection: Use the key finding related to Medication Dosage Calculation and Unit Conversion to guide bedside assessment, documentation, and the next nursing action.
Accurate dosage calculation is a fundamental nursing responsibility to ensure patient safety and prevent medication errors, which can have severe or fatal consequences.
Always follow the 'Ten Rights' of medication administration: right patient, drug, dose, route, time, documentation, assessment, education, evaluation, and right to refuse.
What if? If the available tablets were 250 mg each, the nurse would administer 1 tablet (250 mg / 250 mg = 1), demonstrating how the available stock directly impacts the calculation.

How to Approach the Question

Step 1: Identify the prescribed dose (0.25 g) and the available dose (125 mg per tablet).
Step 2: Notice the units are different (grams vs. milligrams). Convert them to a single, consistent unit. It's usually easiest to convert the larger unit (grams) to the smaller unit (milligrams).
Step 3: Recall or look up the conversion factor: 1 g = 1000 mg.
Step 4: Perform the conversion: 0.25 g × 1000 = 250 mg.
Step 5: Apply the dosage calculation formula: (Required Dose / Available Dose) = Number of tablets.
Step 6: Substitute the values: (250 mg / 125 mg) = 2. The answer is 2 tablets.

Concept Tested & Keywords

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