There are 2 tons of coal, 1500 kilograms have been used up, how many kilograms are left?
有2吨煤，用掉了1500千克，还剩多少千克？
<gadget id="calculator">2 * 1_000</gadget>
<output>2_000</output>

<gadget id="calculator">2_000 - 1_500</gadget>
<output>500</output>

<result>500</result>