Prime number theorem: A big deal is known about the distribution of prime numbers and of the prime factors of a typical number. Most of the mathematics, although, is deep: while the results are often not too hard to state, the proofs are often difficult. We will introduce one fundamental and extremely significant theorem about the distribution of prime numbers. (Its proof is one of the difficult ones!)
Let x be any positive number. We denote by Π (x) the number of prime numbers less than or equal to x. The prime number theorem was conjectured by Gauss in the year 1791 (at the age of 14!), but was not proved until 1896, when it was proved independently through Jacques Hadamard and Charles de la Vallee Poussin.
(Remember that ln x denotes the natural logarithm of x: ln x = loge x.)