An acrobat performs a tightrope walk on a unicycle. The diameter of the wheel is 40 centimeters. To ride a 31.4-meter-long steel wire, how many revolutions does the wheel have to make?
杂技演员表演独轮车走钢丝，车轮的直径40厘米，要骑过31.4米长的钢丝，车轮要转多少周？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3.14 * (2/5)</gadget>
<output>1.256</output>

<gadget id="calculator">31.4 / 1.256</gadget>
<output>25</output>

<result>25</result>