kind of refrigerator, the original price is 2400 yuan, the promotional price is 1800 yuan, what percentage is cheaper?
一种电冰箱，原价是2400元，促销价是1800元，便宜了百分之几？
<gadget id="calculator">2_400 - 1_800</gadget>
<output>600</output>

<gadget id="calculator">600 / 2_400</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>