If the circumference of the large circle is twice that of the small circle, what is the diameter of the large circle when the diameter of the small circle is 2 decimeters?
如果大圆的周长是小圆的2倍，当小圆的直径是2分米时，大圆的直径是多少分米．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<result>4</result>