[tex]\bf ~~~~~~~~~~~~\textit{negative exponents}\\\\
a^{-n} \implies \cfrac{1}{a^n}
\qquad \qquad
\cfrac{1}{a^n}\implies a^{-n}
\qquad \qquad
a^n\implies \cfrac{1}{a^{-n}}\\\\
-------------------------------\\\\
e^{-2}\implies \cfrac{1}{e^2}[/tex]
plug that in your calculator, yes, your calculator has an [ e ], button for the Euler's constant.