A sheep is tied to a 5-meter-long rope and tied to a tree stump in the middle of the grass. How far can the sheep eat grass?
一根长5米的绳子系着一只羊，栓在草地中央的树桩上，羊所能吃到草的范围有多大？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<result>78.5</result>