On a 1:4000 map, measure a rectangular fish pond with a length of 4 cm and a width of 2.5 cm. What is the actual area of the fish pond in square meters?
在一幅1：4000地图上，量得一个长方形鱼池的长4cm，宽2.5cm，这个鱼池的实际占地面积是多少平方米．
<gadget id="calculator">1 / 4_000</gadget>
<output>1/4_000 = around 0.00025</output>

<gadget id="calculator">4 / (1/4_000) / 100</gadget>
<output>160</output>

<gadget id="calculator">2.5 / (1/4_000) / 100</gadget>
<output>100</output>

<gadget id="calculator">160 * 100</gadget>
<output>16_000</output>

<result>16_000</result>