The hour hand of the clock goes from pointing 6 to pointing 9, how many degrees does the hour hand rotate around the center of the clock?
钟表的时针从指向6到指向9，时针绕钟表的中心旋转了多少度．
<gadget id="calculator">360 / 12</gadget>
<output>30</output>

<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<result>90</result>