$12 \frac{5}{7} + 23 \frac{3}{5} - 14 \frac{1}{3} = 28 \frac{4}{7} - ?$

The value of $\frac{3}{1^{2} \cdot 2^{2}}+\frac{5}{2^{2} \cdot 3^{2}}+\frac{7}{3^{2} \cdot 4^{2}}+\frac{9}{4^{2} \cdot 5^{2}}+\frac{11}{5^{2} \cdot 6^{2}}+\frac{13}{6^{2} \cdot 7^{2}}+\frac{15}{7^{2} \cdot 8^{2}}+\frac{17}{8^{2} \cdot 9^{2}}+\frac{19}{9^{2} \cdot 10^{2}}$ is

What is the value of $\frac{5.6 \times 0.36 + 0.42 \times 3.2}{0.8 \times 2.1} ?$

When simplified,the product $\left(2-\frac{1}{3}\right)\left(2-\frac{3}{5}\right)\left(2-\frac{5}{7}\right) \ldots \left(2-\frac{999}{1001}\right)$ is equal to

If $x=\sqrt{\frac{\sqrt{5}+1}{\sqrt{5}-1}},$ then the value of $5x^{2}-5x-1$ is

If $x * y = x^{2} + y^{2} - xy$,then the value of $9 * 11$ is