Maple Leaf Garment Factory received the task of producing a batch of shirts, and produced 600 pieces in the first 4 days, completing 40% of the task. According to this calculation, how many days will it take to complete this task?
枫叶服装厂接到生产一批衬衫的任务，前4天生产600件，完成了任务的40%．照这样计算，完成这项任务一共需要多少天？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 4</gadget>
<output>1/10 = around 0.1</output>

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

<result>10</result>