Proste dodawanie cyfr w stringu

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp9
{
    class Program
    {
        static void Main(string[] args)
        {
            string numerki = "123456";
            int suma = 0;
            for(int i=0;i<numerki.Length;i++)
            {
                suma += (int)numerki[i];
            }
            Console.WriteLine(suma);

            Console.ReadKey();
        }
    }
}

static void Main(string[] args)
        {
            string numerki = "123456";
            int suma = 0;
            foreach (char i in numerki)
            {
                suma += (int)Char.GetNumericValue(i);
            }
            Console.WriteLine(suma);

            Console.ReadKey();
        }

            string number = "123456";
            var sum = number.Sum(c => c - '0');

    var number = "123456";
    var sum = number.Sum(c => int.Parse(c.ToString()));