There are 840 ping-pong balls, 6 are packed in a box, and 10 boxes are packed in a box. How many boxes are needed in total?
有840个乒乓球，每6个装一盒，每10盒装一箱，一共需要装多少箱？
<gadget id="calculator">840 / 6 / 10</gadget>
<output>14</output>

<result>14</result>