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If you grab the URL variable topic after the . up to the delimiter and add the index of the div elements under quickModForm then send this to the quick reply and force post you can autopost the current number.
Instead of grabbing the URL variable you can get the current thread page number, subtract that by one and times it by 15 (in the 15 per thread view) before you add the last page's values, if there are none on the last page then make sure 0 is added and not null. You may also want to make a failsafe for the posting script in case someone else posts. This can be done as a in browser script or a program (provided with the correct credentials and a web interface and HTML source reader for such.