Xiao Ming formed a rectangle with a length of 12 cm and a width of 6 cm with a wire. If the largest square is surrounded by this wire, what is the side length of the square?
小明用一根铁丝围成了一个长12厘米，宽6厘米的长方形．如果用这根铁丝围一个最大的正方形，正方形的边长是多少？
<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>

<result>9</result>