Mod10 algorithm function on c#

Mod10Algorithm.cs

private int Mod10Check(string creditCardNumber)
{
    //// 1.	Starting with the check digit double the value of every other digit 
    //// 2.	If doubling of a number results in a two digits number, add up
    ///   the digits to get a single digit number. This will results in eight single digit numbers                    
    //// 3. Get the sum of the digits
    int sumOfDigits = creditCardNumber.Where((e) => e >= '0' && e <= '9')
                    .Reverse()
                    .Select((e, i) => ((int)e - 48) * (i % 2 == 0 ? 1 : 2))
                    .Sum((e) => e / 10 + e % 10);


    //// If the final sum is divisible by 10, then the credit card number
    //   is valid. If it is not divisible by 10, the number is invalid.            
    return sumOfDigits % 10;
}