3 tons of iron nails are put into 100 wooden boxes, and there are 500 kilograms left. How many wooden boxes are needed?
铁钉3吨，装进100只木箱后，还剩500千克，还需要多少只木箱．
<gadget id="calculator">3 * 1_000</gadget>
<output>3_000</output>

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

<gadget id="calculator">2_500 / 100</gadget>
<output>25</output>

<gadget id="calculator">500 / 25</gadget>
<output>20</output>

<result>20</result>