Zhang Qiang reads a book, 125 pages a day, and after 18 days, there are 309 pages left. How many pages does this book have?
张强看一本书，每天看125页，看了18天后还剩309页没看．这本书一共有多少页？
<gadget id="calculator">125 * 18</gadget>
<output>2_250</output>

<gadget id="calculator">2_250 + 309</gadget>
<output>2_559</output>

<result>2_559</result>