Obviously running around the 400-meter runway of the school playground for two weeks, how many meters are left is exactly 1 kilometer.
明明绕学校操场400米的跑道跑两周，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">400 * 2</gadget>
<output>800</output>

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

<result>200</result>