Each bookshelf has 5 layers, and each layer holds 40 books. How many books can be placed on the 3 bookshelves?
每个书架有5层，每层放40本书，3个书架一共可以放多少本书？
<gadget id="calculator">40 * 5 * 3</gadget>
<output>600</output>

<result>600</result>