How many books has Carolyn Keene writing in the Nancy Drew series?

Carolyn Keene is a pseudonym, not an actual author. The Nancy Drew series was written by a team of ghostwriters, including:

* Mildred Wirt Benson wrote the majority of the early books.

* Walter Karig and Harriet Adams also wrote several books.

* Later authors include Andrew Neiderman, James D. Kuhl, and Mary Rodgers.

There are over 175 Nancy Drew books, but it's impossible to say how many Carolyn Keene wrote specifically, as the authorship is attributed to the pseudonym.