$\frac{3}{5}$ of $\frac{4}{7}$ of $\frac{5}{9}$ of $\frac{21}{24}$ of $504 = ?$

On simplification of $\frac{(2.644)^{2}-(2.356)^{2}}{0.288},$ we get

$1+\frac{1}{2}+\frac{1}{4}+\frac{1}{7}+\frac{1}{14}+\frac{1}{28}$ is equal to

What fraction must be subtracted from the sum of $\frac{1}{4}$ and $\frac{1}{6}$ to have an average of $\frac{1}{12}$ of all the three fractions?

$\left(\frac{24}{9}\right)^{2} \times \frac{399}{39} \div \frac{41}{899} = ?$

The value of $\sqrt{2 \sqrt[3]{4 \sqrt{2 \sqrt[3]{4 \sqrt{2 \sqrt[3]{4 \ldots}}}}}}$ is