The signal light at a traffic intersection changes once every 30 seconds. If it changes to a red light at 5:00 pm, how many times will it change at 5:10?
某交通路口的信号灯每30秒转换-次，如果下午5时刚转换成红灯，到5时10分要转换多少次？
<gadget id="calculator">600 / 30</gadget>
<output>20</output>

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

<result>21</result>