At 9:00 am on November 15, 2003, the "Shenzhou-5" manned spacecraft was ignited and lifted off. At 6:36 am on the 16th, the "Shenzhou-5" spacecraft was successfully recovered. It took 21:36 in the middle, how many hours in total.
2003年11月15日上午9时，"神州五号"载人飞船点火升空，16日上午6时36分"神州五号"飞船回收成功，中间经过了21时36分，合计多少时．
<gadget id="calculator">15 + 6.6</gadget>
<output>21.6</output>

<result>21.6</result>