It is stipulated that a*b=(a+b)/2, then 1998*2000=how much.
规定a*b=(a+b)/2，那么1998*2000=多少．
<gadget id="calculator">1_998 + 2_000</gadget>
<output>3_998</output>

<gadget id="calculator">3_998 / 2</gadget>
<output>1_999</output>

<result>1_999</result>