A bridge is 500 meters long, and street lights are installed on the poles on both sides of the bridge. If there is a pole every 50 meters, and two street lights are installed on each pole, how many street lights should be installed in total?
一座大桥长500米，给桥两边的电杆上安装路灯，若每隔50米有一棵电杆，每棵电杆上安装2盏路灯，一共要安装多少盏路灯？
<gadget id="calculator">500 / 50</gadget>
<output>10</output>

<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<gadget id="calculator">11 * 2</gadget>
<output>22</output>

<gadget id="calculator">22 * 2</gadget>
<output>44</output>

<result>44</result>