The hour hand of a wall clock is 7 cm long, what is the area swept by the hour hand in one circle?
一只挂钟的时针长7厘米，这根时针走一圈扫过的面积是多少？
<gadget id="calculator">7 ** 2</gadget>
<output>49</output>

<gadget id="calculator">3.14 * 49</gadget>
<output>153.86</output>

<result>153.86</result>