FOR løkke

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace For_lokke
{
    public partial class Form1 : Form
    {
        int tal = 0;
        public Form1()
        {
            InitializeComponent();
        }

        private void btnKlikPaaMig_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < 10; i++)
            {
                tal = tal + i;
                lstUd.Items.Add("i = " + i + " "+ tal);
            }
        }
    }
}