Digging a 1,800-meter-long canal, 840 meters was dug in 7 days. At this speed, how many days will it take to complete such a project?
挖一条长1800米的水渠，7天挖了840米，照这样的速度，完成这样的工程还需多少天？
<gadget id="calculator">1_800 - 840</gadget>
<output>960</output>

<gadget id="calculator">840 / 7</gadget>
<output>120</output>

<gadget id="calculator">960 / 120</gadget>
<output>8</output>

<result>8</result>