processing factory processes 540 parts. It has been processing for 4 days, and 115 parts are processed every day. How many parts are left unprocessed?
某加工厂加工540个零件，已经加工了4天，每天加工115个，还有多少个零件没有加工？
<gadget id="calculator">115 * 4</gadget>
<output>460</output>

<gadget id="calculator">540 - 460</gadget>
<output>80</output>

<result>80</result>