The symbol \(e\) represents Euler's constant. It is approximately \(2.7182818285\). There are an infinite number of digits. It turns out that if \(\htmlId{tooltip-function}{f}(\htmlId{tooltip-var}{x}) = e^{\htmlId{tooltip-var}{x}}\), then \(\htmlId{tooltip-function}{f}(\htmlId{tooltip-var}{x}) = e^{\htmlId{tooltip-var}{x}}\) as well. By extension, if \(\htmlId{tooltip-function}{f}(\htmlId{tooltip-var}{x})= e^{x}\), then \(\htmlId{tooltip-integral}{\int} \htmlId{tooltip-function}{f}(\htmlId{tooltip-var}{x}) \htmlId{tooltip-diff}{\:d} \htmlId{tooltip-var}{x} \equiv \htmlId{tooltip-function}{f}(\htmlId{tooltip-var}{x}) \equiv e^{\htmlId{tooltip-var}{x}}\) as well.