Students in three classes in the third grade participated in the weeding labor. Each class was divided into three groups, with an average of 15 students in each group. How many people in the third grade participated in the weeding labor?
三年级3个班的同学参加除草劳动，每个班分成3组，平均每组有15人，三年级参加除草劳动的一共有多少人？
<gadget id="calculator">15 * 3 * 3</gadget>
<output>135</output>

<result>135</result>