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