Take a piece of square paper whose circumference is 16 decimeters, cut it into the largest circle, then what is the circumference of the circle in decimeters?
用一张正方形纸周长是16分米，把它剪成一个最大的圆形，那么圆的周长是多少分米．
<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>