In a school in Guangzhou, the total number of students in 2007 was 3,000, and the per capita possession of books was 6.8. In 2008, the total number of students was 3,600, and the per capita possession of books was 7. The total number of books in the school's library in 2008 increased compared to 2007. How many copies.
广州某学校2007年学生总人数是3000若人，人均占有图书是6.8本，2008年学生总人数是3600人，人均占有图书是7本，该校图书馆2008年图书总册数比2007年增加多少本．
<gadget id="calculator">3_600 * 7</gadget>
<output>25_200</output>

<gadget id="calculator">3_600 * 6.8</gadget>
<output>24_480</output>

<gadget id="calculator">25_200 - 24_480</gadget>
<output>720</output>

<result>720</result>