On a 50:1 map, measure the length of the tool to be 20 cm, ask how many centimeters the actual tool is.
在一个50：1的地图上，量得工具长为20厘米，问实际工具为多少厘米．
<gadget id="calculator">50 / 1</gadget>
<output>50</output>

<gadget id="calculator">20 / 50</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>