cow is tied to a field of grass. If the rope to tie the cow is 6 meters long, how many square meters of grass can the cow eat at most?
在一片草地上拴着一头牛，如果拴牛的绳子长6米，这只牛最多可以吃到多少平方米的草？
<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">3.14 * 36</gadget>
<output>113.04</output>

<result>113.04</result>