On October 15, 2003, my country's "Shenzhou 5" manned spacecraft was launched at 9:00 a.m. and returned at 6:00 a.m. on October 16. How many hours did "Shenzhou 5" spend in space travel?
2003年10月15日，我国的"神州五号"载人飞船于上午9时升空，到10月16日上午6时才返回，"神州五号"太空旅行共花了多少小时？
<gadget id="calculator">24 - 9</gadget>
<output>15</output>

<gadget id="calculator">15 + 6</gadget>
<output>21</output>

<result>21</result>