Identify the odd term in the list: 1, 4, 9, 16, 23, 25, 36.

Aptitude Odd Man Out and Series Difficulty: Easy
Choose an option
  • A
    9
  • B
    23
  • C
    25
  • D
    36
  • E
    None of these

Answer

Correct Answer: 23

Explanation

Introduction / Context:The sequence is dominated by perfect squares with a single intrusion. Recognizing squares at a glance is the fastest approach to identifying the non-matching term.

Given Data / Assumptions:

  • Squares present: 1(=1^2), 4(=2^2), 9(=3^2), 16(=4^2), 25(=5^2), 36(=6^2)
  • 23 is not a perfect square

Concept / Approach:Confirm each as a square or not, and pick the sole non-square as the odd item.

Step-by-Step Solution:Check 23: it lies between 16 and 25; √23 ≈ 4.796, not integerAll others equal n^2 for integer nHence, 23 is the odd term

Verification / Alternative check:Prime factorization also shows 23 is prime and not a square of any integer.

Why Other Options Are Wrong:9/25/36 are perfect squares and belong in the square set.

Common Pitfalls:Confusing 25 with 5^3 (it is 5^2); mixing cube recognition with square recognition.

Final Answer:23

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