One circle of the school playground is 400 meters, obviously ran a circle around the playground, how many meters are left is exactly 1 kilometer.
学校操场一圈是400米，明明绕着操场跑了一圈，还差多少米正好是1千米．
<gadget id="calculator">1 * 1_000</gadget>
<output>1_000</output>

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

<result>600</result>