Calculate (1/(1x2))﹢(1/(2x3))﹢(1/(3x4))﹢(1/(4x5))=how much.
计算(1/(1x2))﹢(1/(2x3))﹢(1/(3x4))﹢(1/(4x5))=多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/3) - (1/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/2) + (1/6) + (1/12) + (1/20)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>