Cut a wooden stick into 21 segments, and each cut takes an equal period of time. The time for one cut is the total time.
把一根木棍截成21段，每截一段时间相等，截一次用的时间是共用时间的多少．
<gadget id="calculator">21 - 1</gadget>
<output>20</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<result>1/20 = around 0.05</result>