数字“七”的奥秘

以七为底的分数：
1/7 = 0.142857142857142857142857142857......
2/7 = 0.285714285714285714285714285714......
3/7 = 0.428571428571428571428571428571......
4/7 = 0.571428571428571428571428571428......
5/7 = 0.714285714285714285714285714285......
6/7 = 0.857142857142857142857142857142......
7/7 = 1

The wonder of the fractions of the number seven