A story book has 210 pages in total, and Xiaojun read 63 pages in 3 days. At this speed, how many days can Xiaojun finish reading this storybook.
一本故事书共210页，小军3天看了63页．照这样的速度，小军多少天能把这本故事书看完．
<gadget id="calculator">63 / 3</gadget>
<output>21</output>

<gadget id="calculator">210 / 21</gadget>
<output>10</output>

<result>10</result>