The school holds a gymnastics performance. There are 4 classes in each of the fourth, fifth and sixth grades. Each class chooses 15 people to participate. How many people participated in the performance?
学校举行体操表演，四、五、六年级各有4个班，每班选15人参加，参加表演的一共有多少人．
<gadget id="calculator">15 * 4 * 3</gadget>
<output>180</output>

<result>180</result>