Clever calculation: (1+(1/3))*(1-(1/3))*(1+(1/4))*(1-(1/4))*…*(1+(1 /99))*(1-(1/99)).
巧算：(1+(1/3))*(1-(1/3))*(1+(1/4))*(1-(1/4))*…*(1+(1/99))*(1-(1/99))．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">100 / 99</gadget>
<output>100/99 = around 1.010101</output>

<gadget id="calculator">(2/3) * (100/99)</gadget>
<output>200/297 = around 0.673401</output>

<result>200/297 = around 0.673401</result>