square with a side length of 9 decimeters is surrounded by a piece of iron wire. How many decimeters of iron wire are used in total?
用一根铁丝围成一个边长为9分米的正方形，一共要用铁丝多少分米．
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<result>36</result>