(1/(1*3*5))+(1/(3*5*7))+(1/(5*7*9))+(1/(7*9*11))+(1 /(9*11*13)).
(1/(1*3*5))+(1/(3*5*7))+(1/(5*7*9))+(1/(7*9*11))+(1/(9*11*13))．
<gadget id="calculator">1 * 3 * 5</gadget>
<output>15</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">3 * 5 * 7</gadget>
<output>105</output>

<gadget id="calculator">1 / 105</gadget>
<output>1/105 = around 0.009524</output>

<gadget id="calculator">5 * 7 * 9</gadget>
<output>315</output>

<gadget id="calculator">1 / 315</gadget>
<output>1/315 = around 0.003175</output>

<gadget id="calculator">7 * 9 * 11</gadget>
<output>693</output>

<gadget id="calculator">1 / 693</gadget>
<output>1/693 = around 0.001443</output>

<gadget id="calculator">9 * 11 * 13</gadget>
<output>1_287</output>

<gadget id="calculator">1 / 1_287</gadget>
<output>1/1_287 = around 0.000777</output>

<gadget id="calculator">(1/15) + (1/105) + (1/315) + (1/693) + (1/1_287)</gadget>
<output>35/429 = around 0.081585</output>

<result>35/429 = around 0.081585</result>