Xiaofang bought a "Dragon Knight" fighting top. After bargaining with the shopkeeper, he only paid 6 yuan, which was 4 yuan cheaper, and how much cheaper it was.
小方购买一种"龙骑士"战斗陀螺，经与店主讨价还价后，只付了6元，便宜了4元，便宜了多少．
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>