The traffic light at a certain intersection changes every 30 seconds. From 5:00 pm to 5:10 pm, how many times can this signal light be changed at most?
某路口的交通信号灯每30秒转换一次，从下午5时到5时10分，这个信号灯最多能转换多少次？
<gadget id="calculator">600 / 30</gadget>
<output>20</output>

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

<result>21</result>