Answer
0.8736
Work Step by Step
If $a\gt0$, $a\ne1$, $b\ne1$, and $x\gt0$, then we know that $log_{a}x=\frac{log_{b}x}{log_{b}a}$.
Therefore, $log_{\pi}e=\frac{log_{10}\pi}{log_{10}e}\approx\frac{0.4343}{0.4971}\approx0.8736$.
Recall that $b$ can be any positive number other than 1.