To draw a circle with a circumference of 15.7 cm, what is the distance between the two feet of the compass in cm?
要画一个周长是15.7厘米的圆，圆规两脚之间的距离应取多少厘米长．
<gadget id="calculator">2 * 3.14</gadget>
<output>6.28</output>

<gadget id="calculator">15.7 / 6.28</gadget>
<output>2.5</output>

<result>2.5</result>