What is the area of a piece of plastic film 30 cm long and 20 cm wide?
一块长30厘米，宽是20厘米的塑料膜，面积是多少平方米．
<gadget id="calculator">20 / 10_000</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">30 * (1/500)</gadget>
<output>3/50 = around 0.06</output>

<result>3/50 = around 0.06</result>