(1/1)+(1/(1+2))+(1/(1+2+3))+(1/(1+2+3+4))+…(1/(1+2) +3+4+...+11)).
(1/1)+(1/(1+2))+(1/(1+2+3))+(1/(1+2+3+4))+…(1/(1+2+3+4+…+11))．
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 - (1/12)</gadget>
<output>11/12 = around 0.916667</output>

<gadget id="calculator">2 * (11/12)</gadget>
<output>11/6 = around 1.833333</output>

<result>11/6 = around 1.833333</result>