The running track of the sports field is 400 meters in a circle. He obviously wants to run 1 kilometer, but he has already run a circle.
运动场跑道是400米一圈，明明想跑1千米，他已经跑了一圈，还要跑多少米才是一千米．
<gadget id="calculator">1 * 1_000</gadget>
<output>1_000</output>

<gadget id="calculator">1_000 - 400</gadget>
<output>600</output>

<result>600</result>