The perimeter of a piece of rectangular paper is 12 centimeters, and 2 pieces of such rectangular paper fit together to form a square. What is the perimeter of the square in centimeters?
一张长方形纸的周长是12厘米，2张这样的长方形纸正好可以拼成一个正方形，这个正方形的周长是多少厘米．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">12 / 2 / 3</gadget>
<output>2</output>

<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<result>16</result>