piece of iron wire can just enclose a rectangle with a length of 18 cm and a width of 6 cm. If this wire is used to form a square, what is the side length of the square in centimeters?
一根铁丝刚好可以围成一个长18cm，宽6cm的长方形，如果用这根铁丝围成一个正方形，正方形的边长是多少厘米？
<gadget id="calculator">18 + 6</gadget>
<output>24</output>

<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<gadget id="calculator">48 / 4</gadget>
<output>12</output>

<result>12</result>