Xiaohong uses a 40 cm long iron wire to form the largest square. What is the side length of this square?
小红用一根长40厘米的铁丝，围成一个最大的正方形，这个正方形的边长是多少？
<gadget id="calculator">40 / 4</gadget>
<output>10</output>

<result>10</result>