Master Wang and Master Li jointly process a batch of parts. Master Wang processed 36 pieces per hour, and Master Li processed 40 pieces per hour. After 8.5 hours of processing at the same time, they just finished the processing task. When completing the task, how many parts did Master Wang process less than Master Li?
王师傅和李师傅共同加工一批零件．王师傅每小时加工36个，李师傅每小时加工40个，他们同时加工8.5小时后，正好完成加工任务．完成任务时，王师傅比李师傅少加工多少个零件？
<gadget id="calculator">40 - 36</gadget>
<output>4</output>

<gadget id="calculator">4 * 8.5</gadget>
<output>34</output>

<result>34</result>