The price of a batch of goods is first reduced by 20%, and then the price is reduced by 20%, what is the original price of this batch of goods.
一批货物先降价20%，再降价20%，这批货物是原价的多少．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) * (4/5)</gadget>
<output>16/25 = around 0.64</output>

<result>16/25 = around 0.64</result>