Uncle Zhang worked from 10 am to 4 pm and processed 90 parts. How many parts does Uncle Zhang process per hour on average?
张叔叔从上午10时一直工作到下午4时，加工了90个零件，张叔叔平均每小时加工多少个零件？
<gadget id="calculator">90 / 6</gadget>
<output>15</output>

<result>15</result>