Question

is a perfect square.

• A. $4900$
• B. $49000$
• C. $490$

Answer 1

The correct option is A $4900$

We know that $49$ is a perfect square so we need to check for exponents of $10$.
$490=7\times 7\times 10$
Here, exponent on $10$ is odd number so $490$ is not a perfect square.
$4900=7\times 7\times 10\times 10$
Here, exponent on $10$ is even number so $4900$ is a perfect square.
$49000=7\times 7\times 10\times 10\times 10$
Here, exponent on $10$ is odd number so $49000$ is not a perfect square.