A square is formed by combining two rectangles with a length of 6 cm and a width of 3 cm. What is its circumference in centimeters?
用两个长是6厘米，宽是3厘米的长方形拼成一个正方形．它的周长是多少厘米？
<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<result>24</result>