100+ Square Root and Cube Root Aptitude Questions Answers - 2

Ans: C

5808 = 2 × 2 × 2 × 2 × 3 × 11 × 11 = 2² × 2² × 3 × 11².

To make it a perfect square, it must be multiplied by 3.

Ans: D

Clearly, the required number must be a perfect square.

Since, a number having 8 as the unit’s digit cannot be a perfect square, so 1,21,108 is not a perfect square.

Ans: C

7! = 7 × 6 × 5 × 4 × 3 × 2 × 1

= 7 × 2 × 3 × 5 × 2² × 3 × 2

= 2⁴ × 3² × 5 × 7.

Thus, the smallest perfect square number which is divisible by 7! is

(2⁴ × 3² × 5 × 7) × (5 × 7)

= 5040 × 35 = 176400.

Ans: A

Clearly, the man was born between 1800 and 1850.

The only perfect square number between 1800 and 1850 is 1849.

And 1849 = (43)².

So, the man was 43 years old in 1849.

Thus, he was born in (1849 – 43) = 1806.

Ans: D

Let (15)² + (18)² - 20 = $$√x$$.

Then, $$√x$$ = 225 + 324 – 20 = 529.

⇔ x = (529)² = 279841.