There are 6 classes of students watching the performance, 45 people in each class, and each person sends out 2 pats, how many pats should be prepared in total?
有6个班的同学看演出，每班45人，每人发2个小手拍拍，一共要准备多少个小手拍拍？
<gadget id="calculator">45 * 6 * 2</gadget>
<output>540</output>

<result>540</result>