Math Logic

Question :
Why isn't 1 a Prime Number ?

Answer :
If 1 is allowed as a prime, then any number could be written as a product of primes in any ways. For example :

    12 = 1 x 2 x 2 x 3
or 12 = 1 x 1 x 2 x 2 x 3
or 12 = 1 x 1 x 1 x 1 x 1 x 2 x 2 x 3

The fact that factoring into primes can only be done in one way is important in mathematics.
An integer greater than 1 is called a prime number if its only positive divisors (factors) are one and itself. Here 1 is left out.
The fundamental theorem of arithmetic states that every positive integer larger than 1 can be written as a product of one or more primes in a way which is unique except possibly for the order of the prime factors.
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