[TestCase("4437113456x49113")]     // Bank card
        public void GetLostNum(string number)
        {
            // Arrange
            int  lostNum;
            bool validate;

            // Act
            lostNum  = Luhn.GetLostNum(number);
            validate = Luhn.Validate(number.Replace("x", lostNum.ToString()));

            // Assert
            Assert.True(validate);
        }