כיצד לבדוק האם מספר הוא ראשוני

Answer 1

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = 0;

            Random rnd = new Random();

            for (int i = 0; i < 20; i++)
            {
                n = rnd.Next(1, 100);
                if (isPrime(n))
                    Console.WriteLine("{0} - Prime", n);
                else
                    Console.WriteLine("{0} - NOT Prime", n);
            }
        }
        static bool isPrime(int n)
        {
            if (n == 0) return false;
            if (n == 1) return false;
            for (int i = 2; i <= (int)Math.Sqrt(n); i++)
            {
                if (n % i == 0)
                    return false;
                else
                    break;
            }
            return true;
        }
    }
}

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