piece of clothing costs 500 yuan, but no one buys it after a 20% discount. The shopkeeper offers another 20% discount.
一件衣服500元，打八折后仍旧没人买，店主再一次打八折，现在这件衣服卖多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">500 * (4/5) * (4/5)</gadget>
<output>320</output>

<result>320</result>