xamarin android 3number seperator - جدا سازی سه رقم سه رقم در زامارین اندروید

private EditText txt_numbertest;

protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.LoginSandoghlayout);

txt_numbertest = FindViewById(Resource.Id.txt_number_test);
txt_numbertest.AfterTextChanged += Txt_numbertest_AfterTextChanged;
}

private void Txt_numbertest_AfterTextChanged(object sender, Android.Text.AfterTextChangedEventArgs e)
{
if (txt_numbertest.Text != null)
{

var text = e.Editable.ToString();
txt_numbertest.AfterTextChanged -= Txt_numbertest_AfterTextChanged;
var formatedText = String.Format("{0:n0}", Convert.ToDouble(text));
txt_numbertest.Text = formatedText;
txt_numbertest.SetSelection(txt_numbertest.Text.Length);
txt_numbertest.AfterTextChanged += Txt_numbertest_AfterTextChanged;
}
}