How to prove whether a number is prime or not in many ways To prove whether a number is a prime, for example, to prove whether the integer n is a prime, let I = 2 and do the divisor in turn until I

How to prove whether a number is prime or not in many ways To prove whether a number is a prime, for example, to prove whether the integer n is a prime, let I = 2 and do the divisor in turn until I

(1) Until I root n, then we write n as the product as follows: n = I * K
This I is the number greater than the root n. at this time, we can see that K is less than the root n, right?
So is it equivalent to us in I