The school held a broadcasting exercise performance. The third, fourth and fifth grades each have 3 classes, and each class selects 20 students to participate. How many people were there in total?
学校举行广播操表演．三、四、五年级各有3个班，每班选20人参加．参加表演的一共有多少人？
<gadget id="calculator">20 * 3 * 3</gadget>
<output>180</output>

<result>180</result>