Calculation: (1/(1*2))+(1/(2*3))+(1/(3*4))+...+(1/(50*51))=how much.
计算：(1/(1*2))+(1/(2*3))+(1/(3*4))+…+(1/(50*51))=多少．
<gadget id="calculator">1 / 51</gadget>
<output>1/51 = around 0.019608</output>

<gadget id="calculator">1 - (1/51)</gadget>
<output>50/51 = around 0.980392</output>

<result>50/51 = around 0.980392</result>