2003*0.999-2004*0.998=how much.
2003*0.999-2004*0.998=多少．
<gadget id="calculator">2_003 * 0.999</gadget>
<output>2_000.997</output>

<gadget id="calculator">2_004 * 0.998</gadget>
<output>1_999.992</output>

<gadget id="calculator">2_000.997 - 1_999.992</gadget>
<output>1.005</output>

<result>1.005</result>