Install street lights on both sides of the 1 km Wan'an Bridge, and install one every 50 meters (both ends must be installed), how many street lights need to be prepared in total.
在1千米的万安大桥两侧安装路灯，每隔50米安装一盏(两端都要安装)，一共需要准备多少盏路灯．
<gadget id="calculator">1_000 / 50</gadget>
<output>20</output>

<gadget id="calculator">1 * 20</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>