public ValidateNumberPage()
        {
            cursorLabel = new LabelCustomFont {
                Text = ">"
            };
            entryNumber = new EntryCustomFont {
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Keyboard = Keyboard.Numeric
            };
            entryNumber.Completed += OnNumberEntryCompleted;

            stackLayout = new StackLayout {
                Padding = new Thickness(16),
                Children = {
                    new LabelCustomFont {
                        Text = "ENTER A CREDIT CARD NUMBER:"
                    },
                    new StackLayout {
                        Children = {
                            cursorLabel, entryNumber
                        },
                        Orientation = StackOrientation.Horizontal,
                        Spacing = 0
                    }
                }
            };

            Content = new ScrollView() {
                Content = stackLayout,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Orientation = ScrollOrientation.Vertical
            };
        }
        void OnNumberEntryCompleted(object sender, EventArgs args)
        {
            var entry = (EntryCustomFont)sender;
            var resultText = "";
            var resultLabel = new DecodeLabel {
                Text = resultText
            };

            if (Mod10Check (entry.Text)) {
                resultLabel.TextColor = Color.FromHex ("#fff");
                resultText = ">__VALID NUMBER";
            } else {
                resultText = ">INVALID NUMBER";
            }

            entry.IsEnabled = false;
            resultLabel.Animate (true, resultText, 10);

            stackLayout.Children.Add (resultLabel);

            entryNumber = new EntryCustomFont {
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Keyboard = Keyboard.Numeric
            };
            entryNumber.Completed += OnNumberEntryCompleted;

            stackLayout.Children.Add (
                new StackLayout {
                    Children = {
                        cursorLabel, entryNumber
                    },
                    Orientation = StackOrientation.Horizontal,
                    Spacing = 0
                }
            );

            entryNumber.Focus ();
        }