$26.5 \%$ of $488 = ?$

What is the largest two-digit prime number?

What is the Arithmetic mean of the first $n$ natural numbers?

If a number is multiplied by $\frac{3}{5}$ of itself,the value so obtained is $3^{2}$ less than $12^{2}$. What is $\frac{5}{3}$ of that number?

$n$ is a whole number which when divided by $4$ gives the remainder $3$. The remainder when $2n$ is divided by $4$ is

$\left[ {8\left\{ {\left( {\frac{{21 \times \sqrt {\frac{9}{{441}}} }}{5} \text{ of } 60\% - \frac{1}{5}} \right) \times 625 + 7} \right\} \div 4} \right] = ?$