# How do you evaluate log_3 81 ?

The answer is $4$.
${\log}_{3} 81$ is the same thing as writing ${3}^{x} = 81$, where you have to solve for $x$. $3$ is the base number.
$3 \cdot 3 \cdot 3 \cdot 3$ is $81$, proving ${3}^{4} = 81$. So, $4$ is the answer.