The printing factory needs to bind a batch of children's books, 640 volumes are bound every day, and it takes 24 days to complete. How many volumes are there in this batch of books?
印刷厂要装订一批少儿读物，每天装订640册，需要24天完成，这批读物共有多少册？
<gadget id="calculator">640 * 24</gadget>
<output>15_360</output>

<result>15_360</result>