A piece of rectangular paper can just be cut into two square papers with a side length of 3 cm. What is the circumference of this paper in cm?
一张长方形纸正好可以裁成两张边长为3厘米的正方形纸，原来这张纸的周长是多少厘米．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>