Look at this series: 14, 28, 20, 40, 32, 64, 26 .... What number should come next?

Appeared in: AIIMS Raipur - 2017 (shift-2)

Explanation

The series follows a simple, repeating two-step pattern.
The first operation is to multiply the current number by 2.
The second operation is to subtract 8 from the new number.
This pattern (Multiply by 2, Subtract 8) repeats consistently.
Applying this to the last correct number (64), the next step is 64 - 8, which equals 56.

Option A: This answer (52) is derived by taking the incorrect number in the series (26) and applying the next operation in the pattern (26 x 2 = 52). This wrongly assumes the anomalous number is part of a valid new sequence.
Option C: This number does not fit the established pattern of multiplying by 2 or subtracting 8.
Option D: This is the result of incorrectly applying the multiplication step again (64 x 2 = 128), when the pattern requires a subtraction step after a multiplication.

Visual 1: Flowchart: A flowchart illustrating the alternating pattern: Start -> Number -> Multiply by 2 -> Result -> Subtract 8 -> Result -> Loop back to 'Multiply by 2'.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Number Series as background academic context rather than a clinical decision trigger.
While not a clinical question, logical reasoning is a core skill tested in nursing entrance and competitive exams.
This skill is essential for nurses in clinical settings for tasks like interpreting data, recognizing trends in vital signs, and making sound decisions under pressure.
What if the pattern was 'add 14, subtract 8'? The series would be 14, 28, 20, 34, 26... The ability to quickly test different hypotheses is key.

How to Approach the Question

First, examine the relationship between the first few numbers (14, 28, 20).
Notice the numbers alternately increase and decrease, suggesting an alternating operation.
Identify the operations: 14 to 28 is x2; 28 to 20 is -8.
Test if this pattern (2, -8) holds for the rest of the series: 202=40 (Correct), 40-8=32 (Correct), 32*2=64 (Correct).
Recognize that the number '26' in the sequence is an error as it breaks the consistent pattern (64-8 should be 56).
Apply the final step of the pattern to the last valid number (64) to find the correct next term: 64 - 8 = 56.

Concept Tested & Keywords

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Practise the full AIIMS Raipur - 2017 (shift-2)

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