【How-to】What is e in a number

The number e , sometimes called the natural number, or Euler’s number, is an important mathematical constant approximately equal to 2.71828. When used as the base for a logarithm, the corresponding logarithm is called the natural logarithm, and is written as ln(x) ⁡ . Note that ln(e)=1 ⁡ and that ln(1)=0 ⁡ .