There is a steel wire that can be wound 50 times on a round iron pipe with a diameter of 10 cm. How long is this steel wire in meters?
有一根钢丝，在一个直径是10厘米的圆铁管上能绕50圈，这根钢丝长多少米．
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3.14 * 10 * (1/2)</gadget>
<output>15.7</output>

<result>15.7</result>