The scale of a map is 1:1000, and the area of a rectangular lawn measured on this map is 4 square centimeters, what is its actual area in square meters?
一幅地图的比例尺是1：1000，在这幅地图上测得一个长方形草坪的面积是4平方厘米，则它的实际面积是多少平方米．
<result>400</result>