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How to prove that a positive integer n is prime if it cannot be divided by any integer between 2 and root n
It is proved that if n is not divisible by any integer from 2 to the root N and is not prime
Then n can be expressed as: n = ab
Where AB is a non-1 positive integer
Because n is not divisible by any integer between 2 and the root n
So a > root n
B > radical n
AB > radical n × radical n = n
This is contradictory to ab = n, so the original proposition is proved
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