Find (1/1), (1/2), (2/2), (1/2), (1/3), (2/3), (3/3), (2/3), ( 1/3), ...(1/2000), (2/2000), ...(2000/2000), (1999/2000), ...(2/2000), (1/2000) the sum of all fractions.
求(1/1)，(1/2)，(2/2)，(1/2)，(1/3)，(2/3)，(3/3)，(2/3)，(1/3)，…(1/2000)，(2/2000)，…(2000/2000)，(1999/2000)，…(2/2000)，(1/2000)所有分数的和．
<gadget id="calculator">1 + 2_000</gadget>
<output>2_001</output>

<gadget id="calculator">2_000 / 2</gadget>
<output>1_000</output>

<gadget id="calculator">2_001 * 1_000</gadget>
<output>2_001_000</output>

<result>2_001_000</result>