Public Sub TextBox5_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged, TextBox2.TextChanged, TextBox3.TextChanged, TextBox4.TextChanged
Dim x As Integer
x = (Val(TextBox1.Text) + Val(TextBox2.Text) + Val(TextBox3.Text) + Val(TextBox4.Text))
TextBox5.Text = x
End Sub