The circumference of a circle is 15.7 cm, what is its radius in cm.
圆的周长是15.7cm，它的半径是多少cm．
<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>