Mr. Lin surrounded the largest square with a rope of 8.4 meters. What is the area of this square?
林老师用一根8.4米的绳子围成一个最大的正方形，这个正方形的面积是多少平方米？
<gadget id="calculator">8.4 / 4</gadget>
<output>2.1</output>

<gadget id="calculator">2.1 * 2.1</gadget>
<output>4.41</output>

<result>4.41</result>