Calculation: (3/(1*5))+(3/(5*9))+(3/(9*13))+…+(3/(1997*2001)).
计算：(3/(1*5))+(3/(5*9))+(3/(9*13))+…+(3/(1997*2001))．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2_000 / 2_001</gadget>
<output>2_000/2_001 = around 0.9995</output>

<gadget id="calculator">(1/4) * (2_000/2_001)</gadget>
<output>500/2_001 = around 0.249875</output>

<gadget id="calculator">3 * (500/2_001)</gadget>
<output>500/667 = around 0.749625</output>

<result>500/667 = around 0.749625</result>