jinak uz mam tohle:

using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 
 namespace ConsoleApplication1
 {
    class Program
    {
        static void Main()
        {
            int a, b, soucet = 0;
            Console.WriteLine("Zadejte cislo");
            a = int.Parse(Console.ReadLine());
            Console.WriteLine("Zadejte 2, cislo");
            b = int.Parse(Console.ReadLine());
            for (;1<= b; )
            {soucet += a; }
            Console.WriteLine("soucet cisel od {0} do {1} je {2}", a, b, soucet);
            Console.ReadLine();
        }
    }
}