A copper wire is 12.56m long, and it just loops 4 times on the cylinder. What is the diameter of this cylinder in m.
一根铜丝长12.56m，正好在圆筒上饶了4圈．这个圆筒的直径多少m．
<gadget id="calculator">12.56 / 4</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 / 3.14</gadget>
<output>1</output>

<result>1</result>