Calculation: (7/(1*10))+(7/(10*19))+(7/(19*28))+…+(7/(82*91)).
计算：(7/(1*10))+(7/(10*19))+(7/(19*28))+…+(7/(82*91))．
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 / 91</gadget>
<output>1/91 = around 0.010989</output>

<gadget id="calculator">1 - (1/91)</gadget>
<output>90/91 = around 0.989011</output>

<gadget id="calculator">7 * (1/9) * (90/91)</gadget>
<output>10/13 = around 0.769231</output>

<result>10/13 = around 0.769231</result>