A rectangular piece of paper is 48 cm long and 36 cm wide. If the paper is to be cut into squares of equal size without any residue, what is the longest side length of the square in centimeters?
一张长方形纸，长48厘米，宽36厘米．要把这张纸裁成大小相等的正方形纸，而无剩余，正方形的边长最长是多少厘米？
<gadget id="calculator">2 * 2 * 3</gadget>
<output>12</output>

<result>12</result>