If a 28 cm long iron wire is used to form a largest square, what is the side length of the square in cm?
用一根28厘米长的铁丝围成一个最大的正方形，正方形的边长是多少厘米．
<gadget id="calculator">28 / 4</gadget>
<output>7</output>

<result>7</result>