public IActionResult Index(HexCalculator model)
        {
            SetViewBagValues();
            if (!ModelState.IsValid)
            {
                return(View());
            }

            String selectedValue = model.SelectedOperation;

            switch (selectedValue)
            {
            case "Add":
                model.ResultInAltBase = model.AdditionResultInHex();
                model.ResultInDecimal = model.AdditionResultInDecimal();
                break;

            case "Subtract":
                model.ResultInAltBase = model.SubtractionResultInHex();
                model.ResultInDecimal = model.SubtractionResultInDecimal();
                break;

            case "Multiply":
                model.ResultInAltBase = model.MultiplicationResultInHex();
                model.ResultInDecimal = model.MultiplicationResultInDecimal();
                break;

            case "Divide":
                model.ResultInAltBase = model.DivisionResultInHex();
                model.ResultInDecimal = model.DivisionResultInDecimal();
                break;
            }

            return(View(model));
        }