This year, potatoes cost 1.8 yuan per 500 grams, an increase of 0.8 yuan over last year. What percentage is the increase over last year?
今年土豆每500克1.8元，比去年增长0.8元，比去年增长了百分之几？
<gadget id="calculator">1.8 - 0.8</gadget>
<output>1</output>

<gadget id="calculator">0.8 / 1</gadget>
<output>0.8</output>

<result>0.8</result>