Two people, A and B, are walking along a road at the same time, on the same place and in the same direction. A travels 6 kilometers per hour, while B travels 1 kilometer in the first hour, 2 kilometers in the second hour, and 3 kilometers in the third hour..., Each 1 hour of travel is 1 km more than the previous 1 hour. After how many hours, B catches up with A.
甲、乙两人同时同地同向沿一条公路行走，甲每小时行6千米，而乙第1小时行1千米，第2小时行2千米，第3小时行3千米…，每行1小时都比前1小时多行1千米．经过多少小时后乙追上甲．
<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<result>11</result>