Answer
4
Work Step by Step
A natural logarithm is a logarithm to base $e$. As shown on page 582, when a natural logarithm is written in the form $ln (x)$, this is equivalent to the expression $log_{e}x$.
Therefore, $ln (e^{4})=log_{e}(e^{4})=4$. We know this, because $(e)^{4}=e^{4}$.
