Master Wang plans to process 50 machine parts, and has been working for 6 hours, processing 7 parts per hour. How many are left unprocessed?
王师傅计划加工50个机器零件，已经工作了6小时，每小时加工7个．还有多少个没有加工？
<gadget id="calculator">7 * 6</gadget>
<output>42</output>

<gadget id="calculator">50 - 42</gadget>
<output>8</output>

<result>8</result>