A 10-meter-long rope is tied to a cow. What is the maximum area in which the cow grazes?
一条10米长的绳子拴住一头牛，这头牛最大的吃草范围是多少平方米．
<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<result>314</result>