M*N means (M+N)/2, (2008*2010)*2009=how much.
M*N表示(M+N)/2，(2008*2010)*2009=多少．
<gadget id="calculator">2_009 + 2_009</gadget>
<output>4_018</output>

<gadget id="calculator">4_018 / 2</gadget>
<output>2_009</output>

<result>2_009</result>