There is a bunch of oranges, take out its (1/21) for the first time, take out the rest (1/20) for the second time, take out the rest (1/19) for the third time, and take out the 19th time for the 20th time For the remaining (1/2), the original orange is how many times the last remaining orange.
有一堆橘子，第一次取出它的(1/21)，第二次取出余下的(1/20)，第三次取出第二次余下的(1/19)，第20次取出第19次余下的(1/2)，则原来的橘子是最后剩下的橘子的多少倍．
<gadget id="calculator">21 / 1</gadget>
<output>21</output>

<result>21</result>