Grandpa Wang, a farmer, tied a cow to the grass to graze with a 10m long rope. How much grass can this cow eat at most?
农民王爷爷用一根10m长的绳子将一头牛拴在草地上吃草．这头牛最多能吃到多大面积的草？
<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

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

<result>314</result>