There are 4 bookshelves in the school library. There are 306 books on each shelf, and 745 books are borrowed. How many books are left?
学校图书馆有4个书架，每个书架上有306本书，借出745本，还剩多少本书？
<gadget id="calculator">306 * 4</gadget>
<output>1_224</output>

<gadget id="calculator">1_224 - 745</gadget>
<output>479</output>

<result>479</result>