What value will come in place of the question mark (?) in the following question? (You are not expected to calculate the exact value)
$21 + 39 \times 2.9 + 8.99 = ?$

Find the smallest fraction which when added to $\frac{2}{5} \times \frac{15}{21} \times \frac{7}{10} \times \frac{3}{8}$ gives a whole number.

Which of the following statement$(s)$ is/are $TRUE$?
$I.$ $\sqrt{144} \times \sqrt{36} \times \sqrt[3]{125} \times \sqrt{121} = 3960$
$II.$ $\sqrt{324} + \sqrt{49} < \sqrt[3]{216} \times \sqrt{9}$

By which least number should $5000$ be divided so that it becomes a perfect square?

The value of $\frac{(243)^{\frac{n}{5}} \times 3^{2n+1}}{9^{n} \times 3^{n-1}}$ is

What will come in the place of the question mark $(?)$ in the following equation?
$(0.64)^{4} \div (0.512)^{3} \times (0.8)^{4} = (0.8)^{?+3}$