There are 6 tons of rice, and 4000 kilograms are transported away, how many tons are left?
有6吨大米，运走了4000千克，还剩多少吨．
<gadget id="calculator">4_000 / 1_000</gadget>
<output>4</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<result>2</result>