To take the bus, each person needs to insert a coin of 1 yuan each time. If the IC card is swiped, the fee will be deducted 0.8 yuan per person each time. How many percent is cheaper per person to swipe a card than to insert a coin?
乘坐公交车每人每次需投币1元，如果刷IC卡，则每人每次扣费0.8元．每人每次刷卡比投币便宜了百分之几？
<gadget id="calculator">1 - 0.8</gadget>
<output>0.2</output>

<gadget id="calculator">0.2 / 1</gadget>
<output>0.2</output>

<result>0.2</result>