Five classes in the third grade participated in the activity of welcoming the China Aerospace Heroes report group. Each class selected 15 students. Each student needed 2 balloons. How many balloons did they need in total?
三年级5个班参加欢迎中国航天英雄报告团活动，每班选15个同学，每个同学要2个气球，一共要多少个气球？
<gadget id="calculator">5 * 15 * 2</gadget>
<output>150</output>

<result>150</result>