Project Euler 8: Largest product in a series (C#)

The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832.

73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
30358907296290491560440772390713810515859307960866
70172427121883998797908792274921901699720888093776
65727333001053367881220235421809751254540594752243
52584907711670556013604839586446706324415722155397
53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881
16427171479924442928230863465674813919123162824586
17866458359124566529476545682848912883142607690042
24219022671055626321111109370544217506941658960408
07198403850962455444362981230987879927244284909188
84580156166097919133875499200524063689912560717606
05886116467109405077541002256983155200055935729725
71636269561882670428252483600823257530420752963450

Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?

Uncomfortably large 1000 digit number is getting stored as a string to begin with.. it's just too big to fit into the regular number types. Thought was I could either iterate through all possible sets of 13 then see if 0 is part of the set. If 0 is part of the set, obviously the product will be 0 which is less than a set without 0.. so just get rid of those possibilities. If we can get a product out of it that isn't 0, we are going to parse each string into its digit using LINQ then aggregate it into a product. Then compare the product to the last highest product. If it is higher, set the current highest product to the new product.

            Stopwatch stopwatch = new Stopwatch();
            stopwatch.Start();
            
            string thousandDigitNum =
                "/*insert giant number here from their website*/";

            string thirteenDigitString = null;
            long newProduct = 0;
            long currHighestProduct = 0;

            for (int i = 0; i < (thousandDigitNum.Length -13); i++)
            {
                thirteenDigitString = thousandDigitNum.Substring(i, 13);
                if (thirteenDigitString.Contains("0")) continue;
                
                newProduct = thirteenDigitString.Select(digit => long
                        .Parse(digit.ToString()))
                        .Aggregate((a, b) => a*b);
                
                if (newProduct > currHighestProduct) currHighestProduct = newProduct;
            }

            stopwatch.Stop();

            Console.WriteLine("The highest value is: " + currHighestProduct + ". And the time elapsed is:" + stopwatch.Elapsed);
            Console.ReadLine();

23514624000 is the solution.