The count of the number of search results is incorrect
Summary: The number of results provided on the search results page is inaccurate.
Cause: The number of results provided on the search results page or in the search results XML is only an estimate, and should not be considered to be an exact count of the number of matching documents.
Workaround: Use the rc=1 request parameter to request an accurate result count for up to 1M documents.
Additional Information: See Estimated vs. Actual Number of Results.