How many days can a cistern be filled with (1/5) of the whole water every day? If the water of the whole pool (1/9) is pumped out every day, how many days can it be drained?
一个蓄水池，每天放人全池水的(1/5)，几天可以放满？如每天抽出全池(1/9)的水，几天可抽干？
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 / (1/9)</gadget>
<output>9</output>

<result>9</result>