Equation question!

How I should resolve (1/(2))^x=16 without the calculator?

$\begin{array}{|rcll|} \hline \left(\frac12 \right)^x &=& 16 \\ \left(\frac12 \right)^x &=& 2^4 \\ \left(\frac12 \right)^x &=& \frac{1}{2^{-4}} \\ \left(\frac12 \right)^x &=& \left(\frac12 \right)^{-4} \\ x &=& -4 \\ \hline \end{array}$