(1/(1+2))+(1/(1+2+3))+(1/(1+2+3+4))+…+(1/(1+2+3+…+ 50)).
(1/(1+2))+(1/(1+2+3))+(1/(1+2+3+4))+…+(1/(1+2+3+…+50))．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 51</gadget>
<output>1/51 = around 0.019608</output>

<gadget id="calculator">(1/2) - (1/51)</gadget>
<output>49/102 = around 0.480392</output>

<gadget id="calculator">2 * (49/102)</gadget>
<output>49/51 = around 0.960784</output>

<result>49/51 = around 0.960784</result>