Fundamental Theorem of Arithmetic

Theorem
For every integer $n$ such that $n > 1$, $n$ can be expressed as the product of one or more primes, uniquely up to the order in which they appear.

Proof
In Integer is Expressible as Product of Primes it is proved that every integer $n$ such that $n > 1$, $n$ can be expressed as the product of one or more primes.

In Prime Decomposition of Integer is Unique, it is proved that this prime decomposition is unique up to the order of the factors.