Cut the largest circle out of a rectangular cardboard with a length of 8 cm and a width of 5 cm. What is the circumference of the circle in decimeters?
在一个长8厘米、宽5厘米的长方形纸板上剪一个最大的圆，圆的周长是多少分米．
<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<result>15.7</result>