If two rectangles with a length of 6 cm and a width of 3 cm are put together to form a square, what is the perimeter of the square in cm?
把两个长是6厘米，宽是3厘米的长方形拼成一个正方形，这个正方形的周长是多少厘米厘米．
<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<result>24</result>