Cut out the largest circle from a square paper with a length of 10 decimeters. What is the circumference of this circle in decimeters?
从一张长10分米的正方形纸里剪下一个最大的圆，这个圆的周长是多少分米．
<gadget id="calculator">3.14 * 10</gadget>
<output>31.4</output>

<result>31.4</result>