The last digit of $10^{n}$ for any integer $n \geq 1$ is ............

Simplify: $\frac{1}{\sqrt{12-\sqrt{140}}}-\frac{1}{\sqrt{8-\sqrt{60}}}-\frac{2}{\sqrt{10+\sqrt{84}}}$

The decimal form of $\frac{12}{35}$ is $\ldots \ldots \ldots \ldots$

The product of any four consecutive positive integers is always divisible by:

Without actually performing the long division,state whether the following rational number will have a terminating decimal expansion or a non-terminating repeating decimal expansion: $\frac{129}{2^{2} \cdot 5^{7} \cdot 7^{5}}$

The decimal form of $\frac{42}{35}$ is $\ldots \ldots \ldots \ldots$