The school bought 12 bookshelves, each with 4 layers, and each layer can hold 45 books. How many books can these bookshelves hold in total?
学校买来12个书架，每个书架有4层，每层可以放45本，这些书架一共可以放多少本？
<gadget id="calculator">45 * 4 * 12</gadget>
<output>2_160</output>

<result>2_160</result>