1 square kilometer = how many square meters.
1平方千米=多少平方米．
<gadget id="calculator">1_000 * 1_000</gadget>
<output>1_000_000</output>

<gadget id="calculator">1 * 1_000_000</gadget>
<output>1_000_000</output>

<result>1_000_000</result>