Install street lamps from beginning to end on one side of a road; the distance between every two street lamps is 30 meters, and the length of the road is 900 meters. How many street lamps need to be installed in total?
在一条路的一边从头到尾安装路灯；每两盏路灯之间相距30米，路长900米，共需要安装多少盏路灯．
<gadget id="calculator">900 / 30</gadget>
<output>30</output>

<gadget id="calculator">30 + 1</gadget>
<output>31</output>

<result>31</result>