Jiong Jiong reads a book and reads 63 pages in the first 3 days. At this speed, he can read the entire book in another 20 days. How many pages does this book have?
炯炯看一本书，前3天看了63页，按这样的速度，再看20天可以看完全书，这本书共有几页？
<gadget id="calculator">63 / 3</gadget>
<output>21</output>

<gadget id="calculator">3 + 20</gadget>
<output>23</output>

<gadget id="calculator">21 * 23</gadget>
<output>483</output>

<result>483</result>