Prime Number Formula

Question

I am trying to write a prime number function in C# and I am wondering if the follow code will work. It \"appears\" to work with the first 50 numbers or so. I just want to ma

Answer 1

Here we must have to consider the square root factor. A prime number can be verified if it is not divisible by any number less than the value of square root of any near number.

static bool isPrime(long number) 
{
    if (number == 1) return false;
    if (number == 2) return true;
    if (number % 2 == 0) return false; //Even number     
    long nn= (long) Math.Abs(Math.Sqrt(number));
    for (long i = 3; i < nn; i += 2)  {
       if (number % i == 0) return false;
    }
    return true;
}