Cong accompanied me to read a 600-page story book, and I have been reading it for 12 days. On average, I read 45 pages a day, how many pages are left unread?
聪陪看一本600页故事书，已经看了12天．平均每天看45页，还剩多少页没有看？
<gadget id="calculator">45 * 12</gadget>
<output>540</output>

<gadget id="calculator">600 - 540</gadget>
<output>60</output>

<result>60</result>