There are 640 books in the school library, placed on 2 bookshelves, each shelf has 8 compartments, how many books are placed in each compartment on average?
学校图书馆有640本书，放在2个书架上，每个书架有8个格，平均每格放多少本？
<gadget id="calculator">640 / 2 / 8</gadget>
<output>40</output>

<result>40</result>