In mathematics, e is a numerical constant that is approximately equal to 2.71828). It is also known as Eulers number or Napiers constant. Like pi, e is an irrational number, which means it cannot be expressed as a fraction. The number e is of great importance in mathematics, alongside 0, 1, π, and i). It appears in one formulation of Eulers identity and plays important and recurring roles across mathematics). The exponential function with base e is particularly suited to doing calculus, and choosing e (as opposed to some other number as the base of the exponential function) makes calculations involving the derivatives much simpler). Eulers number is used to express the base of the natural logarithm. It is commonly used in a wide range of applications, including population growth of living organisms and the radioactive decay of heavy elements like uranium by nuclear scientists. It can also be used in trigonometry, probability, and other areas of applied mathematics.