In a ratio of 1:100000, the distance between A and B is 21 cm, what is the actual distance between A and B in kilometers?
在比例为1：100000，甲、乙两地相距21厘米，甲乙两地的实际距离是多少千米．
<gadget id="calculator">100_000 / 100_000</gadget>
<output>1</output>

<gadget id="calculator">21 * 1</gadget>
<output>21</output>

<result>21</result>