The original price of a product is 420 yuan, now the discount is 20%, how much is the current price?
一件商品原价420元，现在优惠20%，现价多少元？
<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">420 * (4/5)</gadget>
<output>336</output>

<result>336</result>