SoftUni - 5.8 Prime Number Check

//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).

using System;

class PrimeNum
{
    static void Main()
    {
        Console.Write("Enter number: ");
        string numA = Console.ReadLine();
        int newNumA = int.Parse(numA);

        while (newNumA <= 0)
        {
            Console.WriteLine("Number is not positive.");
            Console.Write("Enter number: ");
            newNumA = int.Parse(Console.ReadLine());
        }

        if ((newNumA == 2) || (newNumA == 3) || (newNumA == 5))
        {
            Console.WriteLine("true");
        }
        else if (((newNumA % 2 == 0) || (newNumA % 3 == 0) || (newNumA % 5 == 0)) || (newNumA == 1))
        {
            Console.WriteLine("false");
        }
        else
        {
            Console.WriteLine("true");
        }
    }
}