private void button_Calculate_Click(object sender, EventArgs e)
        {
            double UserInput;
            double price;
            double discount;
            if(double.TryParse(textBox_Input.Text, out UserInput))
            {
                if (UserInput > -1 && UserInput < 10)
                {
                    //discount 0%
                    discount = 99 * 0.0;
                    price = 99 - discount;
                    label_Discount_Output.Text = discount.ToString();
                    label_Output_Price.Text = price.ToString();
                }

                if (UserInput > 9 && UserInput < 20)
                {
                    //discount 20%
                    discount = 99 *0.2;
                    price = 99 - discount;
                    label_Discount_Output.Text = discount.ToString();
                    label_Output_Price.Text = price.ToString();
                }

                else if (UserInput > 19 && UserInput < 50)
                {
                    //discount 30%
                    discount = 99 * 0.3;
                    price = 99 - discount;
                    label_Discount_Output.Text = discount.ToString();
                    label_Output_Price.Text = price.ToString();
                }

                else if (UserInput > 49 && UserInput < 99)
                {
                    //discount 40%
                    discount = 99 * 0.4;
                    price = 99 - discount;
                    label_Discount_Output.Text = discount.ToString();
                    label_Output_Price.Text = price.ToString();
                }

                else if (UserInput > 99)
                {
                    //discount 50%
                    discount = 99 * 0.5;
                    price = 99 - discount;
                    label_Discount_Output.Text = discount.ToString();
                    label_Output_Price.Text = price.ToString();
                }


            }

            else
            {
                MessageBox.Show("Please input a numerical amount");
            }
        }