The number 81 is 3 raised to which power?

The number 81 is 3 raised to which power :  3^4 = 81

$$\small{\text{
\begin{array}{rcl}
3^x &=& 81 \quad | \quad \ln{()} \\\\
\ln{(3^x)} &=& \ln{(81)} \\\\
x*\ln{(3)} &=& \ln{(81)} \\\\
x &=& \frac{ \ln{(81)} } {\ln{(3)} } \\\\
x &=& 4
\end{array}
}}$$

$$\boxed{3^4 = 81}$$

3^1  =  3

3^2  =  3 x 3  =  9

3^3  =  3 x 3 x 3  =  81