The issue is that the number of results is often an estimate for performance reasons. So the results should say something like "around X results" or "approximat

The issue is that the number of results is often an estimate for performance reasons. So the results should say something like "around X results" or "approximately X results" to make that clearer. If Google or some other search-based service had to check every document for a match to verify that the results were accurate (to avoid false positives and negatives) then 1) search would be slow; 2) it would be expensive; and 3) the search couldn't handle many requests (as that would kill the database server). What search engines/databases tend to do is make use of fast and efficient lookup tables or indices, then perform operations on those results (such as joining between different tables) depending on the particular search terms/options (e.g. if you are searching for a specific content type or timeframe). There is a lot of complexity in making the numbers and results both accurate and efficient.