The runway is 400 meters per lap, how many kilometers is 2 and a half laps.
跑道每圈400米，2圈半是多少千米．
<gadget id="calculator">2 * 400</gadget>
<output>800</output>

<gadget id="calculator">400 / 2</gadget>
<output>200</output>

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

<gadget id="calculator">1_000 / 1_000</gadget>
<output>1</output>

<result>1</result>