C# Determine if Given Number is a Multiple of 3

using System;

class PowerOfThree
{
    // Entry Point 
    public static void Main()
    {
        Console.WriteLine("Enter number: ");
        int userInput = Convert.ToInt32(Console.ReadLine());

        if (CheckMultiple(userInput) != 0)
            Console.Write("\n{0} is a multiple of 3.", userInput);
        else
            Console.Write("\n{0} is not a multiple of 3.", userInput);

        Console.Read();
    }
    
    static int CheckMultiple(int n)
    {
        int odd = 0, even = 0;

        if (n < 0) n = -n; if (n == 0) return 1; if (n == 1) return 0; while (n != 0) { if ((n & 1) != 0) odd++; n = n >> 1;
            if ((n & 1) != 0)
                even++;

            n = n >> 1;
        }

        return CheckMultiple(Math.Abs(odd - even));
    }    
}

 

Output