A steel factory produced 580 tons of steel in April and 456 tons of steel in May, sold 730 tons, how many tons are left unsold.
某钢铁厂4月份生产钢铁580吨，5月份生产钢铁456吨，售出了730吨，还剩多少吨未售出．
<gadget id="calculator">580 + 456</gadget>
<output>1_036</output>

<gadget id="calculator">1_036 - 730</gadget>
<output>306</output>

<result>306</result>