How many books has Isaac Asimov sold?

While it's impossible to know the exact number of Isaac Asimov's books sold across all formats and editions throughout history, it is widely accepted that he was one of the best-selling science fiction authors of all time, selling millions of copies.

Here's why getting a precise number is difficult:

* No central record: There isn't a single source tracking all book sales across different publishers, formats (paperback, hardback, ebooks), and countries.

* Sales over decades: Asimov published prolifically for over 50 years, and his books continue to be reprinted and sold.

* Different editions: Each book has various editions, adding to the complexity of tracking sales.

However, estimates suggest that Asimov's books have sold hundreds of millions of copies worldwide.

This is confirmed by his consistent placement on various "best-selling science fiction authors" lists and the enduring popularity of his works.