For one hour, the minute hand is 40 cm long, how many square centimeters does the minute hand sweep in one hour?
一个钟，分针长40厘米，一小时分针所扫过的地方有多少平方厘米．
<gadget id="calculator">40 ** 2</gadget>
<output>1_600</output>

<gadget id="calculator">3.14 * 1_600</gadget>
<output>5_024</output>

<result>5_024</result>