for i in range(1, 10): for j in range(1, i + 1): print("%s * %s = %s" % (i, j, i * j), end="\t") print()

这是一个Python编程中的双重循环示例，通常用于打印乘法表。它会遍历从1到9的所有整数`i`，然后对于每个`i`值，再遍历从1到`i`的所有整数`j`。`print()`函数里的字符串模板`"%s * %s = %s"`用于格式化输出，表示`i`和`j`相乘的结果。`end="\t"`使得每行的输出之间用制表符分隔，而不是换行。外层循环结束后，会打印一个空行来开始新的一行乘法表。

简单来说，这段代码的效果就是：

1 * 1 = 1	
1 * 2 = 2	2 * 2 = 4	
1 * 3 = 3	2 * 3 = 6	3 * 3 = 9	
1 * 4 = 4	2 * 4 = 8	3 * 4 = 12	4 * 4 = 16	
1 * 5 = 5	2 * 5 = 10	3 * 5 = 15	4 * 5 = 20	5 * 5 = 25	
1 * 6 = 6	2 * 6 = 12	3 * 6 = 18	4 * 6 = 24	5 * 6 = 30	6 * 6 = 36	
1 * 7 = 7	2 * 7 = 14	3 * 7 = 21	4 * 7 = 28	5 * 7 = 35	6 * 7 = 42	7 * 7 = 49	
1 * 8 = 8	2 * 8 = 16	3 * 8 = 24	4 * 8 = 32	5 * 8 = 40	6 * 8 = 48	7 * 8 = 56	8 * 8 = 64	
1 * 9 = 9	2 * 9 = 18	3 * 9 = 27	4 * 9 = 36	5 * 9 = 45	6 * 9 = 54	7 * 9 = 63	8 * 9 = 72	9 * 9 = 81