Use two iron wires of the same length to form a parallelogram and a square respectively. The lengths of the two adjacent sides of the parallelogram are 12 cm and 8 cm respectively. What is the side length of the square in centimeters?
用两根一样长的铁丝刚好分别做成一个平行四边形和一个正方形，量得平行四边形相邻的两条边长分别是12厘米和8厘米，那么正方形的边长是多少厘米．
<gadget id="calculator">12 + 8</gadget>
<output>20</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">40 / 4</gadget>
<output>10</output>

<result>10</result>