\begin{definition}[Definition:Euler's Number/Decimal Expansion]
The decimal expansion of Euler's number $e$ starts:
:$2 \cdotp 71828 \, 18284 \, 59045 \, 23536 \, 02874 \, 71352 \, 66249 \, 77572 \, 47093 \, 69995 \ldots$
{{OEIS|A001113}}
\end{definition}