Xiaojun reads a story book and reads 25 pages a day. After reading it for 5 days, he reads exactly half of the book. How many pages does the book have?
小军看一本故事书，每天看25页，看了5天后，正好看了这本书的一半，这本书共有多少页？
<gadget id="calculator">25 * 5 * 2</gadget>
<output>250</output>

<result>250</result>