There are 210 books in class 5.1 and 240 books in class 5.2. The books of these two classes just account for 1/3 of the whole grade. How many books are there in the whole grade of fifth grade?
班级建立图书角，5.1班有图书210本，5.2班有图书240本，这两个班的图书正好占整个年级的(1/3)，求五年级全年级共有图书多少本？
<gadget id="calculator">210 + 240</gadget>
<output>450</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">450 / (1/3)</gadget>
<output>1_350</output>

<result>1_350</result>