library has 12 identical bookshelves, each shelf has 3 layers, and each layer holds 250 books. How many books can these bookshelves hold in total?
一个图书馆有12个同样的书架，每个书架有3层，每层放250本书．这些书架一共能放多少本书？
<gadget id="calculator">12 * 3 * 250</gadget>
<output>9_000</output>

<result>9_000</result>