Even some of the most basic and easily accessible bits, like indexation, can leave one scratching their head, trying to figure out what is the "right" number. Of course, the reality is that there are no right numbers . . . just right now numbers. On the web though, right now is often measured by the click of a mouse or hitting "Enter."
At best, we often hope to find something that is closer to reality than anything else. It is less about the number, but the relationship of numbers from month to month, and how those numbers compare to the number of URLs we believe "exist" for a site.
Along with the advanced search operators detailed in the guide, there are also parameters that can be appended. In playing around with this several months ago, I couldn't help but chuckle and think that I "broke" Google for a second. Rest assured, Google seems to have recovered nicely, but you too can experience this for your own amusement.
After doing any kind of search, you can append the "num=100" parameter to the query string to get 100 results instead of the default 10. Another useful parameter is the "start=990" that takes you to the last page of the results, without having to click through to the end.
To recreate, just append the following to the URL query string in the address bar of your browser after running a query in Google:
Combining these two not only lead to a result I wasn't expecting - no results - but also a situation that I think Google just wasn’t ready to handle. Poor Google . . . I made it drop an "o" . . . uh oh.