The students plant trees on both sides of a 120-meter-long road, and plant one tree every 6 meters (both ends should be planted). How many saplings are needed in total?
同学们在一条长120米的道路两旁植树，每隔6米栽一棵(两端要栽)，一共需要多少棵树苗？
<gadget id="calculator">120 / 6</gadget>
<output>20</output>

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

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<result>42</result>