Select the option to replace ? to maintain the pattern in given number series.

1, 1, 2, 6, 24, ?, 720

Appeared in: RRB Staff Nurse Ahmedabad-2015

Explanation

The series follows a sequential multiplication pattern.
Each term is multiplied by a consecutively increasing integer (1, 2, 3, 4, ...) to obtain the next term.
The pattern is: 1 (×1) → 1 (×2) → 2 (×3) → 6 (×4) → 24.
To find the missing term, you must multiply the previous term (24) by the next integer in the sequence (5).
Calculation: 24 × 5 = 120.
The subsequent step confirms the pattern: 120 × 6 = 720.

Option A: 100 does not fit the established pattern of sequential multiplication. Multiplying 24 by 5 results in 120, not 100.
Option B: 104 is not the result of multiplying 24 by 5. It does not follow the logical sequence of the series.
Option C: 108 is incorrect. The pattern requires multiplying by 5 at this step, not a different number. 24 × 5 = 120.

Visual 1: Flowchart. A flowchart illustrating the step-by-step calculation: starting with 1, showing an arrow labeled '×1' pointing to 1, then an arrow labeled '×2' pointing to 2, and so on, highlighting the '×5' step to arrive at 120.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Logical Reasoning: Number Series Pattern Recognition as background academic context rather than a clinical decision trigger.
While not a clinical question, it tests logical reasoning and pattern recognition, which are crucial skills for nurses.
Nurses use pattern recognition to identify trends in a patient's vital signs, lab results, or symptoms, which can indicate improvement or deterioration.
Strong analytical skills are essential for accurate medication dosage calculations, IV drip rate adjustments, and interpreting complex data.

How to Approach the Question

First, carefully observe the sequence of numbers provided: 1, 1, 2, 6, 24, ?, 720.
Analyze the relationship between consecutive numbers. Ask yourself if they are related by a common difference (addition/subtraction) or a common ratio (multiplication/division).
Test the relationship: 1 to 1 (×1 or +0), 1 to 2 (×2 or +1), 2 to 6 (×3 or +4), 6 to 24 (×4 or +18).
Identify the consistent pattern. The multiplication pattern (×1, ×2, ×3, ×4) is much simpler and more consistent than the addition pattern.
Apply the identified pattern to find the missing number. Multiply the last known number (24) by the next integer in the sequence (5).
Verify your answer by applying the pattern to the next number in the series. Check if 120 × 6 equals 720, which it does.

Concept Tested & Keywords

Q17kXS-FjuocppIpVzgGzx

Practise the full RRB Staff Nurse Ahmedabad-2015

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