A rectangular piece of paper is 28 cm long and 22 cm wide. Leave 2 cm blank on the four sides of the paper, and then divide the middle rectangle into several identical squares. What is the longest side length of the square?
一个长方形纸片长28厘米，宽22厘米，在纸的四边留2厘米的空白，然后把中间的长方形分成若干个相同的正方形．正方形的边长最大是多少厘米？
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<result>6</result>