A piece of paper is 60 cm long and 45 cm wide. If you want to cut it into a square of the same size without any residue, what is the longest side length of the square in cm?
一张纸长60厘米，宽45厘米，要把它剪成同样大小的正方形而没有剩余，正方形的边长最长是多少厘米？
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>