(1/(1*2))+(1/(1*2*3))+(1/(1*2*3*4))+(1/(1*2*3*4*5) )+(1/(1*2*3*4*5*6)).
(1/(1*2))+(1/(1*2*3))+(1/(1*2*3*4))+(1/(1*2*3*4*5))+(1/(1*2*3*4*5*6))．
<gadget id="calculator">1 * 2</gadget>
<output>2</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 * 2 * 3</gadget>
<output>6</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 * 2 * 3 * 4</gadget>
<output>24</output>

<gadget id="calculator">1 / 24</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">1 * 2 * 3 * 4 * 5</gadget>
<output>120</output>

<gadget id="calculator">1 / 120</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">1 * 2 * 3 * 4 * 5 * 6</gadget>
<output>720</output>

<gadget id="calculator">1 / 720</gadget>
<output>1/720 = around 0.001389</output>

<gadget id="calculator">(1/2) + (1/6) + (1/24) + (1/120) + (1/720)</gadget>
<output>517/720 = around 0.718056</output>

<result>517/720 = around 0.718056</result>