Assume that there are a fixed number of prime numbers. P1, P2, P3, ... Pn
Let h = (P1•P2•P3 ... Pn)+1
This means h is not divisible by any prime number. (you will get 1 as remainder)
This gives an absurd result as all number greater than 1 are divisible by a prime number.
Hence, the initial assumption is false. This means there are infinitely many prime numbers.
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Proving for all n<1, n is divisible by a prime number.
Let r be the smallest divisor of n, where r is not 1.
If r is not a prime number, then there exists a v which is a divisor of r, where 1
v is a divisor of r => v is divisor of n
This gives an absurd result as we took r as the smallest divisor of n.
Therefore r is a prime.