C#-Code

using System;
using System.Linq;

namespace CS_Aufgabe_288_Summe_Ungerader_Zahlen
{
    class Program
    {
        static void Main(string[] args)
        {
            var lst = Enumerable.Range(10, 10).Where(x => x % 2 != 0);
            Console.WriteLine($"Die Summe der Zahlen {string.Join(", ", lst)} beträgt {lst.Sum()}");
        }
    }
}

C#-Code

using System;
using System.Collections.Generic;
using System.Linq;

namespace odd_numbers
{
    class Program
    {

        static void Main(string[] args)
        {
            List<int> oddnumbers = new List<int>();

            for (int i = 10; i <= 20; i++)
            {
                if (i % 2 != 0)
                {
                    oddnumbers.Add(i);
                }
            }
            Console.WriteLine(oddnumbers.Sum());
            Console.ReadKey();
        }
    }
}

C#-Code

using System;

namespace Summe_ungerader_Zahlen
{
    class Program
    {
        static void Main(string[] args)
        {
            int summe = 0;
            for(int i = 10; i <= 20; i++)
            {
                if(i % 2 == 1) { summe += i; }
            }
            Console.WriteLine(summe);
            Console.ReadLine();
        }
    }
}

C#-Code

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

namespace Summe_ungerade_Zahlen
{
    class Program
    {
        static void Main(string[] args)
        {
            double[] zahlen = new double[] { 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };

            var ungeradeQuery = zahlen.Where((x) => x % 2 != 0);

            double[] ungeradeZahlen = ungeradeQuery.ToArray();

            double summe = 0;

            for(int i = 0; i < ungeradeZahlen.Length; i++)
            {
                summe = summe + ungeradeZahlen[i];
            }

            Console.WriteLine($"Dies Summe aller ungeraden Zahlen von 10 - 20 ist: {summe}");

            Console.ReadKey();
        }
    }
}

C#-Code

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

namespace Ungerade_Zahlen
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Anzahl von ungeraden Zahlen.");
            int unten = 10;
            int oben = 20;
            int counter = 0;
            while (oben != unten)
            {
                int test=oben%2;
                if (test == 1)
                {
                    counter++;
                }
                oben--;
            }
            Console.WriteLine($"Die Anzahl der ungeraden Zahlen sind: {counter}.");
            Console.Read();
        }
    }
}