The movement of the minute hand of a clock can be regarded as a phenomenon of rotation. The minute hand of a standard clock rotates at a constant speed. How many degrees does it rotate after 15 minutes?
钟表分针的运动可看做一种旋转现象，一只标准时钟的分针匀速旋转，经过15分钟旋转了多少度．
<gadget id="calculator">6 * 15</gadget>
<output>90</output>

<result>90</result>