Draw the largest circle inside a square with a circumference of 40 cm. What is the circumference of this circle?
在一个周长40cm的正方形内画一个最大的圆，这个圆的周长是多少？
<gadget id="calculator">40 / 4</gadget>
<output>10</output>

<gadget id="calculator">3.14 * 10</gadget>
<output>31.4</output>

<result>31.4</result>