The natural constant e is lim(1+1/x)^x, x→+∞ or lim(1+z)^(1/z), z→0. Its value is approximately 2.71828, which is an infinite non-repeating number.

e, as a mathematical constant, is the base of the natural logarithm function. It is sometimes called the Euler number, named after the Swiss mathematician Euler; it is also less commonly known as the Napier constant, in honor of the Scottish mathematician John Napier who introduced logarithms. Like pi and the imaginary unit i, e is one of the most important constants in mathematics.