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replied on March 29, 2015
Sorry for the late response, I was out of the office for the week. Now that I'm looking at this question again, that method is probably not the best way to handle this situation mainly because of the inability to handle simultaneous requests. In case you're interested though, this is how you would do it:
Essentially you would have a document or folder that would be hidden from users. On that entry you will assign a field value. It can be whatever name you want. It should be a number field. The next step is pretty straightforward. It will look something like this:

Keep in mind that you should be assigning the number to something other than the Starting Entry. The image above is just an example.
This method will work fine for demos but I would not recommend it for a production environment. As Ben mentioned earlier, I would recommend using SQL to handle the incremental numbering.