Imports System.Collections.Generic 
  Imports System.Drawing 
  Imports System.Windows.Forms 
  Imports System.Linq 
   
  Public Partial Class MainForm 
  	Inherits Form 
  	Public Sub New() 
   
   
  		InitializeComponent() 
  	End Sub 
   
  	Private Shared Sub Yalnızsayı(sender As Object, e As KeyPressEventArgs) 
   
   
  		If Not Char.IsControl(e.KeyChar) AndAlso Not Char.IsDigit(e.KeyChar) AndAlso (e.KeyChar <> "."C) Then 
  			e.Handled = True 
  		End If 
   
  	End Sub 
   
  	Private Sub Button1Click(sender As Object, e As EventArgs) 
  		textBox3.Text = (Convert.ToDouble(textBox1.Text) * 0.2 + Convert.ToDouble(textBox2.Text) * 0.8).ToString() 
  	End Sub 
   
  	Private Sub MainFormLoad(sender As Object, e As EventArgs) 
  		For Each textBox As TextBox In Controls.OfType(Of TextBox)() 
  			AddHandler textBox.KeyPress, AddressOf Yalnızsayı 
  			AddHandler textBox.TextChanged, AddressOf sayı 
  		Next 
  	End Sub 
   
  	Private Sub sayı(sender As Object, e As EventArgs) 
   
  		For Each textBox As TextBox In Controls.OfType(Of TextBox)() 
   
  			If textBox.Text <> "" Then 
  				If Convert.ToDouble(textBox.Text) > 100 Then 
   
  					textBox.Text = "100" 
  				End If 
   
  			End If 
  		Next 
  	End Sub 
   
  End Class