TeX source:

\log _{\pi} \mathrm{e}=\frac{\log (\mathrm{e})}{\log (\pi)} \approx \mathbf{0 . 8 7 3 5 6 8 5} \approx \frac{\ln (\mathrm{e})}{\ln (\pi)}=\frac{1}{\ln (\pi)}