999*999-2*999+1.
999*999-2*999+1．
<gadget id="calculator">999 * 999</gadget>
<output>998_001</output>

<gadget id="calculator">2 * 999</gadget>
<output>1_998</output>

<gadget id="calculator">998_001 - 1_998</gadget>
<output>996_003</output>

<gadget id="calculator">996_003 + 1</gadget>
<output>996_004</output>

<result>996_004</result>