section_path: Properties/Number theory
section_name: Number theory
paragraph_text: Number theory
  
  The real number e is irrational. Euler proved this by showing that its simple continued fraction expansion does not terminate. (See also Fourier 's proof that e is irrational.)
  
  Furthermore, by the Lindemann–Weierstrass theorem, e is transcendental, meaning that it is not a solution of any non-zero polynomial equation with rational coefficients. It was the first number to be proved transcendental without having been specifically constructed for this purpose (compare with Liouville number); the proof was given by Charles Hermite in 1873.
  
  It is conjectured that e is normal, meaning that when e is expressed in any base the possible digits in that base are uniformly distributed (occur with equal probability in any sequence of given length).
  
  In algebraic geometry, a period is a number that can be expressed as an integral of an algebraic function over an algebraic domain. The constant π is a period, but it is conjectured that e is not.