There are 9 groups in Class 3, 6 people in each group. They planted a total of 216 trees on Arbor Day. How many trees are planted per person on average?
三1班一共有9个小组，每个小组6人，他们在植树节一共植树216棵．平均每人植树多少棵？
<gadget id="calculator">216 / 9 / 6</gadget>
<output>4</output>

<result>4</result>