The least perfect square, which is divisible by each of 21, 36 and 66 is

Answer: Option D

Answer: Option B

Explanation:

\begin{aligned}
= \sqrt[3]{\frac{512}{125}} \end{aligned}
\begin{aligned}
= (\frac{8*8*8}{5*5*5})^{\frac{1}{3}} \end{aligned}

\begin{aligned} = \frac{8}{5} = 1\frac{3}{5} \end{aligned}

Answer: Option C

Explanation:

\begin{aligned}
= \sqrt{\frac{25}{16}}
\end{aligned}

\begin{aligned}
= \frac{\sqrt{25}}{\sqrt{16}}
\end{aligned}

\begin{aligned}
= \frac{5}{4}
\end{aligned}

\begin{aligned}
= 1\frac{1}{4}
\end{aligned}

Answer: Option B

Explanation:

\begin{aligned}
=> \sqrt{81} + \sqrt{0.81} = 10.09 - X
\end{aligned}

\begin{aligned}
=> 9 + 0.9 = 10.09 - X
\end{aligned}

\begin{aligned}
=> X = 10.09 - 9.9 = 0.19
\end{aligned}

Answer: Option A

Explanation:

\begin{aligned}
3600 = 2^3 \times 5^2 \times 3^2 \times 2
\end{aligned}
To make it a perfect cube it must be divided by
\begin{aligned}
5^2 \times 3^2 \times 2 = 450
\end{aligned}