If a rectangle with a length of 12 cm and a width of 9 cm is changed into a square, what is the area of the square in square centimeters?
一根铁丝长12厘米，宽9厘米的长方形，改成一个正方形，求正方形的面积是多少平方厘米？
<gadget id="calculator">12 + 9</gadget>
<output>21</output>

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<gadget id="calculator">42 / 4</gadget>
<output>21/2 = around 10.5</output>

<gadget id="calculator">(21/2) * (21/2)</gadget>
<output>441/4 = around 110.25</output>

<result>441/4 = around 110.25</result>