Calculation: (9991*1991.1991+9991.9991*1999)/2.0002.
计算：(9991*1991.1991+9991.9991*1999)/2.0002．
<gadget id="calculator">9_991 * 1_999 * 1.0001</gadget>
<output>19_974_006.2009</output>

<gadget id="calculator">9_991 * 1.0001 * 1_999</gadget>
<output>19_974_006.2009</output>

<gadget id="calculator">19_974_006.2009 + 19_974_006.2009</gadget>
<output>39_948_012.4018</output>

<gadget id="calculator">39_948_012.4018 / 2.0002</gadget>
<output>19_972_009</output>

<result>19_972_009</result>