* No official, complete record exists. While publishers keep track of sales, they don't typically release exact numbers for every book.
* Multiple editions and translations. The book has been reprinted many times in different editions and languages, making it hard to track all sales.
* E-books and audiobooks. The rise of digital formats makes tracking sales even more difficult.
However, we can say that "Charlie and the Chocolate Factory" is one of the most popular and successful children's books of all time. It has been a consistent bestseller for decades and has been adapted into numerous films and other media, further boosting its popularity.
Therefore, it's safe to assume that millions upon millions of copies have been sold worldwide.