[tex]\bf \qquad \textit{Continuously Compounding Earned Amount}
\\\\
A=Pe^{rt}
\quad
\begin{cases}
A=\textit{accumulated amount}\\
P=\textit{original amount deposited}\to &\$400\\
r=rate\to 9\%\to \frac{9}{100}\to &0.09\\
t=years\to &3
\end{cases}
\\\\\\
A=400e^{0.09\cdot 3}[/tex]
notice, "e" is the Euler's constant, and yes, is on your calculator.
