There is a cow tied with a rope 8 meters long on a wide grassland. How many square meters of grass can this cow eat at most?
宽阔的草地上有一头牛用一条8米长的绳子拴着，这头牛最多能吃到多少平方米的草？
<gadget id="calculator">8 ** 2</gadget>
<output>64</output>

<gadget id="calculator">3.14 * 64</gadget>
<output>200.96</output>

<result>200.96</result>