The school library bought back 210 science and technology books, and bought back three times as many story books as science and technology books. How many story books are there?
学校图书室买回科技书210本，买回的故事书是科技书的3倍，故事书有多少本？
<gadget id="calculator">210 * 3</gadget>
<output>630</output>

<result>630</result>