check binary divisibility

namespace NumberDivisible
{
    using System;
    using System.Linq;

    class Program
    {
        static void Main(string[] args)
        {
            //int[] num = { 9, 2, 5, 8, 1 };
            Console.WriteLine("enter a binary number: ");
            string input = Console.ReadLine();
            //long decimalValue = ToDecimal("101010");
            long decimalValue = ToDecimal(input);
            Console.WriteLine($"Base 10 representation: {decimalValue}");
            int[] nums = decimalValue.ToString().Select(c => int.Parse(c.ToString())).ToArray();
            int sum = Calc(nums, nums.Length - 1);
            bool isDivisibleBy3 = sum % 15 == 0 || sum % 5 == 0 || sum % 3 == 0;
            Console.WriteLine(isDivisibleBy3);
            Console.ReadLine();
        }



        public static long ToDecimal(string binary)
        {
            // 0001
            long value = 0;

            int j = 0;
            for (int i = binary.Length - 1; i >= 0; i--)
            {
                value += (binary[i] == '1' ? 1 : 0) * (int)Math.Pow(2, j++);
            }
            return value;
        }

        public static int Calc(int[] numChar, int i)
        {
            if (i < 0)
            {
                return 0;
            }
            return numChar[i] + Calc(numChar, i - 1);
        }
    }
}