Code review

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace ExtraOefLabo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        string click = "";
        private void btnOk_Click(object sender, RoutedEventArgs e)
        {
            //Input
           
            //Proccess

            //Output
            if (click == "9382")
            {
                MessageBox.Show("Cracked the code!");

            }
        }

        private void btnNr1_Click(object sender, RoutedEventArgs e)
        {
            click+= "1";
        }

        private void btnNr2_Click(object sender, RoutedEventArgs e)
        {
            click +=  "2";
        }

        private void btnNr3_Click(object sender, RoutedEventArgs e)
        {
            click +=  "3";
        }

        private void btnNr4_Click(object sender, RoutedEventArgs e)
        {
            click +="4";
        }

        private void btnNr5_Click(object sender, RoutedEventArgs e)
        {
            click += "5";
        }

        private void btnNr6_Click(object sender, RoutedEventArgs e)
        {
            click += "6";
        }

        private void btnNr7_Click(object sender, RoutedEventArgs e)
        {
            click += "7";
        }

        private void btnNr8_Click(object sender, RoutedEventArgs e)
        {
            click += "8";
        }

        private void btnNr9_Click(object sender, RoutedEventArgs e) 
        {
            click += "9";
        }

        private void BtnNr0_Click(object sender, RoutedEventArgs e)
        {
            click += "0";
        }

        private void btnEnd_Click(object sender, RoutedEventArgs e)
        {
            Application.Current.Shutdown();
        }
    }
}