A bottle of mineral water sells for 2 yuan in retail. In order to thank the customers for their love for this product, the shopping mall specially launched a big bargain activity of "buy four and get one free".
一种矿泉水，零售每瓶卖2元，商场为感谢广大顾客对该产品的厚爱，特开展"买四赠一"大酬宾活动，商场的做法优惠了多少．
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">10 - 8</gadget>
<output>2</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>