Liu Ming read a novel. He read 30 pages on the first day. From the second day on, he read 3 pages more than the previous day. On the 11th day, he read 60 pages, which was just finished. How many pages does this novel have.
刘明读一本小说，他第一天读了30页，从第二天起，他每天读的页数都比前一天多3页，第11天读了60页，正好读完．这本小说共有多少页．
<gadget id="calculator">30 + 60</gadget>
<output>90</output>

<gadget id="calculator">11 / 2</gadget>
<output>11/2 = around 5.5</output>

<gadget id="calculator">90 * (11/2)</gadget>
<output>495</output>

<result>495</result>