However, this is indeed a very rough estimate because the parameter 100...100000 also captures the number that indicates how long ago a user account was created, so it would also count accounts that were created a while ago (over 100 days) but were inactive.

http://google.com/search?hl=en&q=site%3Anews.ycombinator...

(search phrase with wildcard and range in it, I didn't even knew this combination was possible)

http://www.google.com/search?sclient=psy&hl=en&biw=1...

Apparently there are a bunch of pages in the index that just go to "No such user" pages (looks like killed spam accounts).

Unfortunately this search also includes people with accounts created between 100 and 100000 days ago, regardless of karma level. Not sure how to filter that out; you can't use the range syntax in between double quotes, it seems.