(1/(1*2))+(2/(1*2*3))+(3/(1*2*3*4))+…++(8/(1*2*3*… *9))=How much.
(1/(1*2))+(2/(1*2*3))+(3/(1*2*3*4))+…++(8/(1*2*3*…*9))=多少．
<gadget id="calculator">1 / 362_880</gadget>
<output>1/362_880 = around 0.000003</output>

<gadget id="calculator">1 - (1/362_880)</gadget>
<output>362_879/362_880 = around 0.999997</output>

<result>362_879/362_880 = around 0.999997</result>