If 8 trees are planted around the school playground, how many trees should be planted in total?
在学校操场四周分别种8棵树，一共需要种几棵？
<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">32 - 4</gadget>
<output>28</output>

<result>28</result>