For a tractor, the diameter of the front wheel is 1/2 of that of the rear wheel. If the front wheel turns 8 times, how many times does the rear wheel turn?
一台拖拉机，前轮直径是后轮的(1/2)，前轮转动8圈，后轮转多少圈．
<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<result>4</result>