Proof That the Set of Prime Numbers is Infinite

Theorem: There are infinitely many prime numbers. Proof: Suppose, contrary to the theorem, that there is only a finite number of primes. Thus, there will be a largest which we can call p. Now define a number n as 1 plus the product of all the primes: n = (2 X 3 X 5 X 7 X 11 X...X p) 1 Is n itself prime or composite? If it is prime then our original supposition is false, since n is larger than the supposed largest prime p. So now let’s consider it composite. This means that it must be div...