The library bought back a batch of books. Each shelf can hold 150 books. There are 12 bookshelves, and there are still 520 books that have not been put in. How many books did the school buy back in total?
图书室买回一批图书，每个书架可放150本书，放了12个书架，还有520本没放进去，学校一共买回多少本图书？
<gadget id="calculator">150 * 12</gadget>
<output>1_800</output>

<gadget id="calculator">1_800 + 520</gadget>
<output>2_320</output>

<result>2_320</result>