Digging a 4,000-meter-long canal was completed in two weeks, the full length was dug in the first week, and 1,800 meters was dug in the second week.
挖一条长4000米的水渠，两个星期挖好，第一个星期挖了全长的多少，第二个星期挖了1800米．
<gadget id="calculator">4_000 - 1_800</gadget>
<output>2_200</output>

<gadget id="calculator">2_200 / 4_000</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>