(2/(1*(1+2)))+(3/((1+2)*(1+2+3)))+(4/((1+2+3)*(1+2 +3+4)))+...+(10/((1+2+3+...+9)*(1+2+3+...+10))).
(2/(1*(1+2)))+(3/((1+2)*(1+2+3)))+(4/((1+2+3)*(1+2+3+4)))+…+(10/((1+2+3+…+9)*(1+2+3+…+10)))．
<gadget id="calculator">1 / 55</gadget>
<output>1/55 = around 0.018182</output>

<gadget id="calculator">1 - (1/55)</gadget>
<output>54/55 = around 0.981818</output>

<result>54/55 = around 0.981818</result>