Question

Aman has 729 coins. He gives some of these coins to his cousin as his birthday gift. The part given away is the square root of 729. How many coins are left with him?

• A. 27
• B. 702
• C. 29
• D. 709

Answer 1

The correct option is B

702

Coins given to his cousin = $\sqrt{729}$

Prime factorisation of 729 is $729=3\times 3\times 3\times 3\times 3\times 3$

So, $\sqrt{729}$ = $\sqrt{\underset{–}{3\times 3}\times \underset{–}{3\times 3}\times \underset{–}{3\times 3}}$

$⟹\sqrt{729}=3\times 3\times 3=27$

Thus, Aman's cousin gets 27 coins as his birthday gift.

So, Aman is left with 729 - 27
= 702 coins