What is the longest book Malorie Blackman has written?

While there isn't definitive information publicly available on the exact word count of Malorie Blackman's books, we can make a pretty good guess based on the length of her most famous series.

The Noughts & Crosses series, which comprises 9 books, is generally considered her longest work. Each book in the series is quite substantial, likely around 100,000 words or more.

Given that the series spans 9 books, the entire Noughts & Crosses series would easily be over 900,000 words. This makes it her longest work by a considerable margin.

It's worth noting that this is an approximation based on the length of other books in the series and comparable works. For a precise answer, you'd need to access the individual word counts for each book in the Noughts & Crosses series.