I have documents that are up to 600 pages long and have headings that are up to 7 digits (e.g. 3.5.3.1.2.1.2 Heading Name). I would like to be able to search the document using the number on the heading. "Find" does not find it. Is there a way to do it?

CK you are correct...

Edit by CK: I assume that you mean headings rather than headers. If I am mistaken, please edit this post and remove my remarks.
What is the difference between headings and headers?