Calculation: (1/(1*2))+(2/(1*2*3))+(3/(1*2*3*4))+(4/(1*2*3*4* 5)).
计算：(1/(1*2))+(2/(1*2*3))+(3/(1*2*3*4))+(4/(1*2*3*4*5))．
<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) + (1/3) + (1/8) + (1/30)</gadget>
<output>119/120 = around 0.991667</output>

<result>119/120 = around 0.991667</result>