Wang Liang started reading a novel on January 5th. If he reads 80 pages a day, he will finish it by January 9th; if he reads 90 pages a day, he will finish it by January 8th. In order not to affect the normal study, Wang Liang plans to reduce the amount of reading every day, and decides to finish reading in a day, so that if he reads page a every day, he will just finish reading it all. How many pages does this novel have?
王亮从1月5日开始读一部小说．如果他每天读80页，到1月9日读完；如果他每天读90页，到1月8日读完．为了不影响正常学习，王亮准备减少每天的阅读量，并决定分a天读完，这样，每天都读a页便刚好全部读完．这部小说共有多少页．
<gadget id="calculator">18 * 18</gadget>
<output>324</output>

<result>324</result>