A library has 25 identical bookshelves, each shelf has 4 layers, and each layer holds 78 books. How many books can these bookshelves hold in total?
一个图书馆有25个同样的书架，每个书架有4层，每层放78本书．这些书架一共能放多少本书？
<gadget id="calculator">78 * 4 * 25</gadget>
<output>7_800</output>

<result>7_800</result>