On a floor plan with a scale of 1:500, the length of a room is measured as 4 cm, what is the actual length in meters?
在比例尺是1：500的平面图上，量得一间房间的长是4厘米，实际长度是多少米．
<gadget id="calculator">1 / 500</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">4 / (1/500)</gadget>
<output>2_000</output>

<gadget id="calculator">2_000 / 100</gadget>
<output>20</output>

<result>20</result>