In the activity of recycling waste batteries, the 42 students in the first class of four years recycled 6 batteries on average; the 35 students in the second class of four years recycled 4 batteries per person on average. Battery?
在回收废电池的活动中，四年一班的42名同学平均每人回收了6节；四年二班的35名同学平均每人回收的4节，这两个班级一共回收了多少节废电池？
<gadget id="calculator">6 * 42</gadget>
<output>252</output>

<gadget id="calculator">4 * 35</gadget>
<output>140</output>

<gadget id="calculator">252 + 140</gadget>
<output>392</output>

<result>392</result>