The diameter of the rear wheel of a tractor is twice that of the front wheel, and the number of turns of the front wheel is 8 turns of the rear wheel.
一台拖拉机得后轮直径是前轮得2倍，后轮转动8圈，前轮转动多少圈．
<gadget id="calculator">2 * 3.14 * 8</gadget>
<output>50.24</output>

<gadget id="calculator">50.24 / 3.14</gadget>
<output>16</output>

<result>16</result>