There are 4 bookshelves in the school library, and 205 books are placed on each shelf. 396 books have been lent out, how many books are left?
学校图书室有4个书架，每个书架上都放了205本书．借出396本，还剩多少本？
<gadget id="calculator">205 * 4</gadget>
<output>820</output>

<gadget id="calculator">820 - 396</gadget>
<output>424</output>

<result>424</result>