The construction of a canal started on November 1st and was originally scheduled to be completed in one month. During the actual construction, the task was completed on November 20. According to this calculation, how much is overfulfilled by the end of November.
修一条水渠，11月1日开工，原定一个月完成．实际施工时，11月20日就完成了任务．照这样计算，到11月底超额完成多少．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

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

<gadget id="calculator">(1/20) * 10</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>