If a wire with a length of 12.4 decimeters is used to form the largest square, what is the area of the square?
用一根长12.4分米的铁丝围成一个最大的正方形，这个正方形的面积是多少．
<gadget id="calculator">12.4 / 4</gadget>
<output>3.1</output>

<gadget id="calculator">3.1 * 3.1</gadget>
<output>9.61</output>

<result>9.61</result>