Calculation: (1/(5*7))+(1/(7*9))+(1/(9*11))+(1/(11*13))+(1/(13*15) ) = how much.
计算：(1/(5*7))+(1/(7*9))+(1/(9*11))+(1/(11*13))+(1/(13*15))=多少．
<gadget id="calculator">5 * 7</gadget>
<output>35</output>

<gadget id="calculator">1 / 35</gadget>
<output>1/35 = around 0.028571</output>

<gadget id="calculator">7 * 9</gadget>
<output>63</output>

<gadget id="calculator">1 / 63</gadget>
<output>1/63 = around 0.015873</output>

<gadget id="calculator">9 * 11</gadget>
<output>99</output>

<gadget id="calculator">1 / 99</gadget>
<output>1/99 = around 0.010101</output>

<gadget id="calculator">11 * 13</gadget>
<output>143</output>

<gadget id="calculator">1 / 143</gadget>
<output>1/143 = around 0.006993</output>

<gadget id="calculator">13 * 15</gadget>
<output>195</output>

<gadget id="calculator">1 / 195</gadget>
<output>1/195 = around 0.005128</output>

<gadget id="calculator">(1/35) + (1/63) + (1/99) + (1/143) + (1/195)</gadget>
<output>1/15 = around 0.066667</output>

<result>1/15 = around 0.066667</result>