Question

$\text{Which of the following numbers is not a perfect cube?}$

• A. $1331$
• B. $625$
• C. $343$
• D. $729$

Answer 1

The correct option is B $625$

$\text{By prime factorisation, we have}$
$343=(7\times 7\times 7)$
$1331=(11\times 11\times 11)$
$729=(9\times 9\times 9)$
$625=(5\times 5\times 5)\times 5$
$\text{By observation, we can clearly say that}625\text{is not a perfect cube}$
$\text{So, the desired answer is}625$