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The smallest natural number by which 392 must be MULTIPLIED to make it a perfect cube is:

A3
B5
C7
D49
Answer & Solution
Correct answer: C. 7
Prime factorise: 392 = 2³ × 7². The prime 7 occurs twice — we need 7³ to have a group of three. So multiply by 7: 392 × 7 = 2744 = 14³. The smallest such multiplier is 7.
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