An acrobat rides a unicycle on a tightrope. The diameter of a unicycle wheel is 45 cm, and the wheel rolls exactly 40 times from one end of the wire to the other. How many meters is this suspended steel wire?
一位杂技演员在悬空的钢丝上骑独轮车．独轮车车轮的直径是45厘米，从钢丝的一端到另一端，车轮正好滚动40圈．这根悬空的钢丝长多少米？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3.14 * 45 * (2/5)</gadget>
<output>56.52</output>

<result>56.52</result>