Apple books is calculated according to the reading progress after reading a book. The specific algorithm is as follows:

1, Apple Books will record the time of opening a book at a time, and calculate the reading time and reading progress.

2. If the reading time is stable every day, then Apple Books will calculate how long it will take to finish reading a book according to my reading time and reading progress.

3. After reading in the market according to the recommendation given by the APPle Book, the Apple Book App will be considered as reading a book.