What does your code look like so far? What are you using to extract the numbers?
Off the top of my head, I recommend using something like regexp to extract the numbers. Here's a quick swag at what it would look like:
11nums = regexp('Example.txt','/D(/d/d/d/d/d/d/d/d/d/d/d)/D','tokens');
This has not been tested.
In theory it looks for an isolated set of numbers, with 11 digits.