By what least number should $324$ be multiplied to get a perfect cube?

$\sqrt[3]{\mathrm{ab}}=\left(\sqrt[3]{\mathrm{a}}\right)\times \left(\sqrt[3]{k}\right)$. The value of $k$ is _____

If $\sqrt[3]{\frac{\mathrm{a}}{\mathrm{b}}}=$$\frac{\sqrt[k]{a}}{\sqrt[k]{b}}$, then $k=$_____.

If $\sqrt[3]{-x}=$$-\sqrt[k]{x}$, then $k=$_____.

$(0.5{)}^3 =$_____