Draw a circle with a circumference of 15.7 meters, what is its radius in decimeters?
画一个周长15.7米的圆，它的半径应取多少分米．
<gadget id="calculator">15.7 * 10</gadget>
<output>157</output>

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

<result>25</result>