Question

What is the smallest number by which $2560$ must be multiplied so that the product is a perfect cube?

• A. $5$
• B. $25$
• C. $10$
• D. $15$

Answer 1

The correct option is B $25$

$2560$ can be written as $2\times 2\times 2\times 2\times 2\times 2\times 2\times 2\times 2\times 5$

$2560=2^9\times 5$

To make it a perfect cube, it needs to be multiplied by $5^2$i.e. $25$.