The runway on the playground is 400 meters in one lap. After Xiaoqiang ran two laps, the number of meters he ran was 1 kilometer.
操场跑道一圈400米，小强跑了两圈后，再跑多少米米就是1千米．
<gadget id="calculator">1 * 1_000</gadget>
<output>1_000</output>

<gadget id="calculator">400 * 2</gadget>
<output>800</output>

<gadget id="calculator">1_000 - 800</gadget>
<output>200</output>

<result>200</result>