If a lawn is to be planted on a square field with a circumference of 36 meters, what is the area of the lawn?
要在一块周长是36米的正方形空地上种草坪，这块草坪的面积是多少？
<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<result>81</result>