Put a circle into a rectangle, the length of the rectangle is 15.7cm, what is the diameter of the circle in cm.
把一个圆拼成一个长方形，长方形的长是15.7cm，圆的直径是多少cm．
<gadget id="calculator">2 / 3.14</gadget>
<output>0.636943</output>

<gadget id="calculator">15.7 * 0.636943</gadget>
<output>10.000005</output>

<result>10.000005</result>