(1+(1/1999)+(1/2000)+(1/2001))*((1/1999)+(1/2000)+(1/2001)+(1/2002))-(1 +1999→(1/2000)+(1/2001)+(1/2002))*((1/1999)+(1/2000)+(1/2001)).
(1+(1/1999)+(1/2000)+(1/2001))*((1/1999)+(1/2000)+(1/2001)+(1/2002))-(1+1999→(1/2000)+(1/2001)+(1/2002))*((1/1999)+(1/2000)+(1/2001))．
<gadget id="calculator">1 / 2_002</gadget>
<output>1/2_002 = around 0.0005</output>

<result>1/2_002 = around 0.0005</result>