piece of iron wire can exactly enclose a square with a side length of 5 cm. What is the length of the wire in cm?
一根铁丝正好可以围成一个边长为5厘米的正方形，这根铁丝的长是多少厘米．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>