Part ACSIR NET June 2025the-sum-of-the-first-n-cubes-is-the-square-of-their-sum

The sum of the first n cubes is the square of their sum

What will be the digit at the unit's place of $1^{3} + 2^{3} + 3^{3} + 4^{3} + 5^{3} + 6^{3} + 7^{3} + 8^{3} + 9^{3}$ ?

A.0
B.5✓ Correct
C.7
D.9

You have the answer. Trap Analysis is why the other three were written.

Not a worked solution repeated four times — the specific reasoning error each wrong option was built to reward, and why this one tests standard counterexample.

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50 are analysed free — try those first.

The trap it tests

Standard counterexample

There is a canonical object that settles this. Recognising it is the whole question.

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Last revised 12 Sept 2026. Found a mistake? Tell us — corrections are the fastest thing we act on.

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