There are 52 people in Class 3 and Class 4, and each person donates 3 books to the school on average. How many books have they donated in total?
三4班有52人，平均每人向学校捐3本书，一共捐了多少本．
<gadget id="calculator">52 * 3</gadget>
<output>156</output>

<result>156</result>