In the following question, select the odd number from the alternatives given below. Check whether each number has a special property (such as being a perfect square). Identify the number that does NOT share that property with the others. (A) 361 (B) 441 (C) 784 (D) 876 (E) 1024

Aptitude Odd Man Out and Series Difficulty: Easy
Choose an option
  • A
    361
  • B
    441
  • C
    784
  • D
    876
  • E
    1024

Answer

Correct Answer: 876

Explanation

Introduction / Context:This odd-one-out problem checks number properties, most commonly perfect squares. A perfect square is an integer that can be expressed as n*n for some whole number n. The odd number is the one that cannot be written as a square, while the others can.

Given Data / Assumptions:

  • A number is a perfect square if it equals n*n for some integer n.
  • We test each option by recalling common squares or checking nearby squares.
  • If several numbers are exact squares and one is not, that one is the odd choice.

Concept / Approach:Recognize perfect squares by memory (like 19^2, 21^2, 28^2) or by checking whether the number lies exactly on a square boundary. Non-squares will fall between two consecutive squares.

Step-by-Step Solution:

361 = 19*19, so 361 is a perfect square. 441 = 21*21, so 441 is a perfect square. 784 = 28*28, so 784 is a perfect square. 1024 = 32*32, so 1024 is a perfect square. 876: nearby squares are 29^2 = 841 and 30^2 = 900. Since 876 is between 841 and 900, it is not a perfect square.

Verification / Alternative check:Another quick check is to compute the integer square root estimate. Since 29^2=841 and 30^2=900, any number between them is not a square. Because 876 lies strictly between these, it cannot be expressed as n*n for an integer n. Hence it is the odd one out.

Why Other Options Are Wrong:

361: equals 19^2, so it follows the perfect-square property. 441: equals 21^2, so it follows the perfect-square property. 784: equals 28^2, so it follows the perfect-square property. 1024: equals 32^2, so it follows the perfect-square property.

Common Pitfalls:A common mistake is assuming any even number is not a square or any number ending in 1 is a square. Another mistake is checking only the last digit. Always confirm by matching to an exact integer multiplication (n*n) or bounding between consecutive squares.

Final Answer:876

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