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

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {

            int n = 0, sum=1;
            do
            {
                sum += n;
                n++;


            } while (n <= 100);
            Console.WriteLine("n:{0}自然数之和为：{1}", n,sum);
            Console.Read();

        }
    }
}

自然数之和