[8521] Which one of the following is NOT a sum of cubes of the first n natural numbers?

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Aptitude

TNPSC G4

10th CBSE Maths

Which one of the following is NOT a sum of cubes of the first n natural numbers?

23409

8521

441

Explanation:

Sum of cubes of first n natural numbers = $[\dfrac{n(n + 1)}{2}]^{2}$
Here the sum of cubes is a perfect square of some number. Figure out if any of the options is not a perfect square. That will be the answer.
1 is a perfect square [Eliminate]
23409 is a perfect square [Eliminate]
8521 is not a perfect square [= Answer]

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