There is a 120-meter-long gravel road in the park. It is planned to plant a tree every 6 meters on one side of the road (both ends must be planted). How many trees are needed in total?
公园里有一条长120米的石子路，计划在路的一边每隔6米栽一棵树(两端都要栽)，共需多少棵树．
<gadget id="calculator">120 / 6</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<result>21</result>