The school library has added 810 books this year. Now these books should be placed on 3 bookshelves on average, and each bookshelf is divided into 6 layers on average. How many books are placed on each layer?
学校图书室今年新增加了810本图书，现在要将这些图书平均放到3个书架上，每个书架又平均分成了6层，每层放几本？
<gadget id="calculator">3 * 6</gadget>
<output>18</output>

<gadget id="calculator">810 / 18</gadget>
<output>45</output>

<result>45</result>