To draw a circle with a circumference of 15.7 decimeters, what is the radius in centimeters?
要画一个周长是15.7分米的圆，半径应取多少厘米．
<gadget id="calculator">15.7 * 10</gadget>
<output>157</output>

<gadget id="calculator">157 / 3.14 / 2</gadget>
<output>25</output>

<result>25</result>