<math> e \approx 2:71828</math> is the scientific constant, the exponential. Euler's number
The number e is an important mathematical constant that is the base of the natural logarithm.
The number e can be defined to be:
<MATH> ln(a) = 1 </MATH>
<MATH> (1 + \frac{1}{n})^n </MATH>
e to anything is positive.
ln is the inverse function.
<MATH> ln(e(x))=x </MATH>
Whenever you see exponentials the first thing you want to do is take the logs.