What is the value of 2.15 × 0.2015 ?

Appeared in: BSF Staff Nurse - 2015

Explanation

The problem requires the multiplication of two decimal numbers: 2.15 and 0.215.
First, multiply the numbers without the decimal points: 215 × 215 = 46225.
Next, count the total number of decimal places in the original numbers. There are two in 2.15 and three in 0.215, for a total of five decimal places.
Place the decimal point five places from the right in the product: 0.46225.
This result matches the first option. It is assumed there was a typo in the original question's value of 0.2015, and it was intended to be 0.215 to match the provided answer.

Option B: This is an incorrect result of the multiplication. It may stem from an arithmetic error during the multiplication of 215 by 215 or incorrect placement of the decimal.
Option C: This is an incorrect result of the multiplication. It represents a calculation mistake.
Option D: This is an incorrect result of the multiplication. Such an error could happen if the numbers were misread or a mistake was made during the calculation process.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Decimal Multiplication as background academic context rather than a clinical decision trigger.
Accurate decimal multiplication is a fundamental non-negotiable skill for nurses, primarily for correct medication dosage calculation. An error can lead to significant underdosing or overdosing.
For example, calculating a weight-based dose like 1.5 mg/kg for a patient weighing 62.3 kg requires precise multiplication (1.5 × 62.3 = 93.45 mg).
What if? If a nurse misplaced the decimal and calculated 2.15 × 21.5 instead of 2.15 × 0.215, the result would be 46.225, a 100-fold overdose, which would likely be fatal.

How to Approach the Question

First, identify that the question is a straightforward multiplication of two decimal numbers.
A useful estimation technique is to round the numbers: 2 × 0.2 = 0.4. This helps you quickly check if the options are reasonable.
To get the exact answer, multiply the numbers as if they were whole numbers (e.g., 215 × 215).
Calculate the product: 215 × 215 = 46225.
Count the total number of digits after the decimal point in both original numbers. In this case (using the corrected 0.215), it's 2 + 3 = 5.
Place the decimal point in your result so it has that total number of decimal places (five places from the right), which gives 0.46225.

Concept Tested & Keywords

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Practise the full BSF Staff Nurse - 2015

Attempt every question from this paper in a timed mock, then review the full solution for each one.