The perimeter of the square is twice the perimeter of the ring. When the ring rolls around the square without slipping and returns to its original position, how many times does the ring turn?
正方形的周长是圆环周长的2倍，当圆环沿正方形无滑动地滚动一周又回到原来的位置时，这个圆环转了多少圈．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>