Question

Find the smallest number by which 405 must be divided, so as to get a perfect square.

• A. 3
• B. 9
• C. 15
• D. 5

Answer 1

The correct option is D

5

Using the prime factorization method we have,

$405=3\times 3\times 3\times 3\times 5$

Pairing the factors we get $(3\times 3)\times (3\times 3)\times 5$

Since 5 does not have a pair, We divide 405 by 5 to get a perfect square.

So, 5 is the number by which it should be divided, to make it a perfect square.