A bridge is 1200 meters long, and there is a street lamp every 10 meters on both sides of the bridge (installed at both ends). If installed from the beginning to the end, how many street lights are there on this bridge?
一座大桥长1200米，在大桥两边每隔10米就有一盏路灯(两端要装)．如果从头到尾安装，这座桥上共有多少盏路灯？
<gadget id="calculator">1_200 / 10</gadget>
<output>120</output>

<gadget id="calculator">120 + 1</gadget>
<output>121</output>

<gadget id="calculator">121 * 2</gadget>
<output>242</output>

<result>242</result>