(1/(1*2))+(2/(1*2*3))+(3/(1*2*3*4))+(4/(1*2*3*4*5) )+(5/(1*2*3*4*5*6))+(6/(1*2*3*4*5*6*7)).
(1/(1*2))+(2/(1*2*3))+(3/(1*2*3*4))+(4/(1*2*3*4*5))+(5/(1*2*3*4*5*6))+(6/(1*2*3*4*5*6*7))．
<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">2 / 6</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">3 / 24</gadget>
<output>1/8 = around 0.125</output>

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

<gadget id="calculator">4 / 120</gadget>
<output>1/30 = around 0.033333</output>

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

<gadget id="calculator">5 / 720</gadget>
<output>1/144 = around 0.006944</output>

<gadget id="calculator">1 * 2 * 3 * 4 * 5 * 6 * 7</gadget>
<output>5_040</output>

<gadget id="calculator">6 / 5_040</gadget>
<output>1/840 = around 0.00119</output>

<gadget id="calculator">(1/2) + (1/3) + (1/8) + (1/30) + (1/144) + (1/840)</gadget>
<output>5_039/5_040 = around 0.999802</output>

<result>5_039/5_040 = around 0.999802</result>