$11.6 + 9.28 + 0.464 - 0.2828 + 0.07 = ?$

Two-fifth of one-fourth of three-seventh of a number is $15$. What is half of that number?

When simplified,the value of the product $\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right) \ldots\left(1-\frac{1}{n}\right)$ equals

$1 \frac{3}{4} + 5 \frac{1}{3} + 3 \frac{2}{5} = ?$

$7 \frac{1}{2}-\left[2 \frac{1}{4} \div\left\{1 \frac{1}{4}-x\left(1 \frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\right\}\right]=3$. Find the value of $x$.

If $M = 0.1 + (0.1)^{2} + (0.001)^{2}$ and $N = 0.3 + (0.03)^{2} + (0.003)^{2}$,then what is the value of $M + N$?