Question

Aman has 729 coins. He gives only a part of these coins to his cousin as his birthday gift. This part is the square root of 729. How many coins did his cousin get?

• A. 27
• B. 9
• C. 12
• D. 81

Answer 1

The correct option is A

27

The square root of 729 should have 3 or 7 in its unit place. Because square of 3 and 7 has 9 in it's units place. Only 27 satisfies this.
Thus, Aman's cousin gets 27 coins as a birthday gift.

Also, we can find the square root using prime factorization as

$729=3\times 3\times 3\times 3\times 3\times 3$

$729=3^6$

Square root of 729 is equal to

$\sqrt{729}=\sqrt{3^6}=3^3=27$