Provide a new operation a*b=((a*b)/(a+b)), then (1/3)*(1/4)=how much.
规定一种新运算a*b=((a*b)/(a+b))，则(1/3)*(1/4)=多少．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</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">(1/3) + (1/4)</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">(1/12) / (7/12)</gadget>
<output>1/7 = around 0.142857</output>

<result>1/7 = around 0.142857</result>