10% of 10 liters of gasoline is poured out, and then 10% is poured out, how many liters are left.
10升汽油倒出10%，再倒出10%，还剩多少升．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">10 * (9/10) * (9/10)</gadget>
<output>81/10 = around 8.1</output>

<result>81/10 = around 8.1</result>