The factory originally had 3 tons of aluminum, and the workshop used 500 kilograms. How many kilograms of aluminum are left in the factory?
工厂原有铝材3吨，车间用去500千克．问工厂还剩多少千克铝材？
<gadget id="calculator">3 * 1_000</gadget>
<output>3_000</output>

<gadget id="calculator">3_000 - 500</gadget>
<output>2_500</output>

<result>2_500</result>