Calculation: (1/(2012*2013))+(1/(2013*2014))+(1/(2014*2015))+(1/2015).
计算：(1/(2012*2013))+(1/(2013*2014))+(1/(2014*2015))+(1/2015)．
<gadget id="calculator">2_012 * 2_013</gadget>
<output>4_050_156</output>

<gadget id="calculator">1 / 4_050_156</gadget>
<output>1/4_050_156 = around 0</output>

<gadget id="calculator">2_013 * 2_014</gadget>
<output>4_054_182</output>

<gadget id="calculator">1 / 4_054_182</gadget>
<output>1/4_054_182 = around 0</output>

<gadget id="calculator">2_014 * 2_015</gadget>
<output>4_058_210</output>

<gadget id="calculator">1 / 4_058_210</gadget>
<output>1/4_058_210 = around 0</output>

<gadget id="calculator">1 / 2_015</gadget>
<output>1/2_015 = around 0.000496</output>

<gadget id="calculator">(1/4_050_156) + (1/4_054_182) + (1/4_058_210) + (1/2_015)</gadget>
<output>1/2_012 = around 0.000497</output>

<result>1/2_012 = around 0.000497</result>