A vegetable field is drawn on a map with a scale of 1:2000, with a length of 5 cm and a width of 4 cm. What is the actual area of this vegetable field in hectares?
一块菜地画在一幅比例尺为1：2000的地图上，长5cm，宽4cm，这块菜地的实际面积为多少公顷？
<gadget id="calculator">1 / 2_000</gadget>
<output>1/2_000 = around 0.0005</output>

<gadget id="calculator">5 / (1/2_000) / 100</gadget>
<output>100</output>

<gadget id="calculator">4 / (1/2_000) / 100 / 10_000</gadget>
<output>1/125 = around 0.008</output>

<gadget id="calculator">100 * (1/125)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>