A rope can form a rectangle with a length of 12 cm and a width of 6 cm. If this rope is used to form a square, what is the area of the square?
一根绳子可以围成一个长12厘米，宽6厘米的长方形，如果用这根绳子围成正方形，这个正方形的面积是多少？
<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">18 * (1/2)</gadget>
<output>9</output>

<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<result>81</result>