Difficulty: Easy
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:
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:
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:
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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