A certain elementary school donated books to the students in the Yushu disaster area. The fourth grade donated 240 books, the fifth grade donated 320 books, the sixth grade donated twice as much as the fourth grade, how many books were donated by the three grades?
某小学为玉树灾区同学捐书，四年级捐240本，五年级捐320本，六年级捐的是四年级的2倍，三个年级共捐多少本？
<gadget id="calculator">240 * 2</gadget>
<output>480</output>

<gadget id="calculator">240 + 320 + 480</gadget>
<output>1_040</output>

<result>1_040</result>