Draw the largest square in a circle with a circumference of 31.4 decimeters. What is the area of this square in square decimeters?
在一个周长是31.4分米的圆中画一个最大的正方形，这个正方形的面积是多少平方分米．
<gadget id="calculator">31.4 / 3.14</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">5 * (5/2) * 4</gadget>
<output>50</output>

<result>50</result>