$\frac{3}{11} \text{ of } \frac{5}{7} \text{ of } (?) = 63$

Find the unit digit in the product $(4387)^{245} \times (621)^{72}$.

The expression $\frac{8.25 \times 8.25 + 6.75 \times 6.75 - 2 \times 8.25 \times 6.75}{8.25 \times 8.25 - 6.75 \times 6.75}$ when simplified equals:

Two numbers differ by $5$. If their product is $336$,then the sum of the two numbers is

The least number of five digits exactly divisible by $88$ is

$\sqrt{2601} - \sqrt{1156} + \sqrt{484} = ?$