Program.cs

using System;
using System.Linq;
namespace HexactaChallenge
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("9, 22, 1, 3 = " + Min(new[] { 9, 22, 1, 3 }));
            Console.WriteLine("10, 1, 1, 1, 1, 14 = " + Min(new[] { 10, 1, 1, 1, 1, 14 }));
            Console.WriteLine("2, 20, 21, 23 = " + Min(new[] { 2, 20, 21, 23 }));
            Console.WriteLine("91, 22, 1, 3 = " + Min(new[] { 91, 22, 1, 3 }));
            Console.WriteLine("112, 113 = " + Min(new[] { 112, 113 }));
            Console.WriteLine("21, 3 = " + Min(new[] { 21, 3 }));

            WaitForEscapeKey();

        }

        public static long Min(int[] numbers)
        {
            var orderedList = numbers.ToList();
            orderedList.Sort((x, y) =>
            {
                var a = int.Parse(string.Format("{0}{1}", x, y));
                var b = int.Parse(string.Format("{0}{1}", y, x));

                return a > b ? 1 : -1;
            });
            return long.Parse(orderedList.Aggregate("", (c, n) => c + n));
        }

     
        
        private static void WaitForEscapeKey()
        {
            do { while (!Console.KeyAvailable) {} } while (Console.ReadKey(true).Key != ConsoleKey.Escape);
        }

    }
}