Private Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
Dim i As Integer = TextBox1.Text.Length - 1
Dim a As Char
If i > -1 Then
a = TextBox1.Text.Remove(0, i)
If a.IsNumber(a) = False Then
TextBox1.Text = TextBox1.Text.TrimEnd(a)
TextBox1.SelectionStart = i + 1
End If
Else
TextBox1.Text = String.Empty
End If
End Sub