Classification – Odd one out (perfect square among non-squares) Among the following integers, three are not perfect squares while exactly one is a perfect square. Identify the perfect square and mark it as the odd one out.
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A626
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B841
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C962
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D1090
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ENone of these
Answer
Correct Answer: 841
Explanation
Introduction / Context:Odd-one-out items often target quick recognition of perfect squares. Being able to spot classic squares like 29^2 = 841 lets you classify efficiently without lengthy computation.
Given Data / Assumptions:
- Candidates: 626, 841, 962, 1090
- Goal: find the single perfect square
- All values are base-10 integers with no extra conditions
Concept / Approach:Recall common squares around 30^2 = 900. Specifically, 29^2 = 841 and 31^2 = 961. Compare each option to see whether it equals k^2 for some integer k. If a number sits strictly between two consecutive squares, it is not a perfect square.
Step-by-Step Solution:841 = 29^2 → perfect square.626 lies between 25^2 = 625 and 26^2 = 676 → not a square.962 lies between 31^2 = 961 and 32^2 = 1024 → not a square.1090 lies between 33^2 = 1089 and 34^2 = 1156 → not a square.
Verification / Alternative check:Square-root estimates: sqrt(841) = 29 exactly; sqrt(626) ≈ 25.0+, sqrt(962) ≈ 31.0+, sqrt(1090) ≈ 33.0+, none integral. Only 841 matches an integer root, confirming it as the unique square.
Why Other Options Are Wrong:
- 626: Not equal to any k^2.
- 962: Not equal to any k^2.
- 1090: Not equal to any k^2.
- None of these: There is one clear square (841).
Common Pitfalls:Assuming that being close to a square (e.g., 626 near 625) implies squareness. Only exact equality to k^2 qualifies.
Final Answer:841