- RRB Staff Nurse Kolkata-2015

RRB Staff Nurse Kolkata-2015

Non Nursing Subjects

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Appeared in: RRB Staff Nurse Kolkata-2015

Explanation

The expression '4!' represents '4 factorial', which is a mathematical operation.
A factorial is the product of all positive integers up to that number.
To calculate 4!, you multiply 4 by each preceding positive integer: 4 × 3 × 2 × 1.
The calculation is: 4 × 3 = 12, then 12 × 2 = 24, and finally 24 × 1 = 24.

Option A: This is an incorrect product. It might result from a simple calculation error.
Option B: This is incorrect. The factorial of a positive integer is always a positive integer. By special definition, 0! (zero factorial) is equal to 1, not 0.
Option D: This is an incomplete calculation, representing only the first step (4 × 3). The calculation must continue by multiplying by the remaining integers (2 and 1).

Visual 1: Infographic - A chart showing the calculation of factorials from 1! to 5! to illustrate the pattern of growth.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of factorials in mathematics as background academic context rather than a clinical decision trigger.
While not a direct clinical skill, understanding basic mathematics, including concepts like factorials, is essential for the General Aptitude and Reasoning sections of nursing entrance exams.
Factorials are a foundational concept in permutations and combinations, which are used in statistics. Nurses may encounter statistical analysis in research articles, so a basic math foundation is beneficial.
What if the question was 5!? The answer would be 5 × 4 × 3 × 2 × 1 = 120.

How to Approach the Question

First, identify the mathematical symbol '!' as representing a factorial operation.
Recall the definition of a factorial: n! is the product of all positive integers from 1 to n.
Write out the expansion for 4!: 4 × 3 × 2 × 1.
Perform the multiplication step-by-step: 4 × 3 = 12, then 12 × 2 = 24, and finally 24 × 1 = 24.
Compare the final result (24) with the given options and select the matching one.

Concept Tested & Keywords

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Practise the full RRB Staff Nurse Kolkata-2015

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