A 2-meter-long iron wire uses up 4 decimeters, and the rest forms a square. What is the side length of the enclosed square?
一根2米长的铁丝，用去了4分米，剩下的围成一个正方形，围成的正方形的边长是多少分米？
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<result>4</result>