3.8 Check Number Up to 100 Is Prime

// Write an expression that checks if given positive integer number n (n ≤ 100) is prime (i.e. it is divisible without remainder only to itself and 1).

namespace _08.PrimeNumberCheck
{
    using System;

    public class PrimeNumberCheck
    {
        public static void Main(string[] args)
        {
            checked
            {
                Console.Write("Enter a whole number, [num <= 100]: ");
                int num = int.Parse(Console.ReadLine());
                bool numIsPrime = false;
                num = Math.Abs(num);
                if ((num == 2 || num == 3 || num == 5 || num == 7) ||
                    num != 1 && num % 2 != 0 && num % 3 != 0 && num % 5 != 0 && num % 7 != 0)
                {
                    numIsPrime = true;
                }

                Console.WriteLine("Given number Is Prime: {0} !", numIsPrime);
            }
        }
    }
}