This one really involves almost more string manipulation than number crunching. Notice how nicely we can get a substring using the brackets. Also notice how chars gives us each character in our substring as something we can enumerate. This means a simple Enumerable helper method to calculate the product (like previous problems did with sum) and the problem become almost a one liner.
The final thing I love about this solution is the use of the DATA pseudo-IO object to store the number. We could use some sort of string literal but this allows us to put the data out of the way of our actual code while still easily accessible to our code.