A piece of iron wire is 2 meters long, and after making two squares with a side length of 2 decimeters, how many decimeters of iron wire are left?
一根铁丝长2米，做成2个边长2分米的正方形后，还剩多少分米铁丝？
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">2 * 4 * 2</gadget>
<output>16</output>

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

<result>4</result>