There is a steel wire that can be wound 10 times around a circular tube with a diameter of 20 cm. What is the length of the steel wire in cm?
有一根钢丝，可在直径是20厘米的圆管上绕10圈，这根钢丝长多少厘米．
<gadget id="calculator">3.14 * 20 * 10</gadget>
<output>628</output>

<result>628</result>