$L.C.M.(115, 25) = \ldots$

State whether the following rational number has a terminating decimal expansion or not. If it does,find it: $\frac{19}{256}$

State whether the following rational number has a terminating decimal expansion or not. If it has a terminating decimal expansion,find it: $\frac{29}{343}$

Prove that one and only one out of every three consecutive positive integers is divisible by $3$.

Prove that $\sqrt{3}+\sqrt{5}$ is irrational.

Show that one and only one out of $n, n+4, n+8, n+12$ and $n+16$ is divisible by $5,$ where $n$ is any positive integer.