回複：4,divided by 9,......the remainders are 4,5,6,7,8,9....

Congratulation! You finally solved 130!

Your answer can also expressed as: The sum of all digits (if more than one digits, sum it recursively) is 4, 5, 6, 7, 8, 9:

1 + 4 = 5
1 + 5 + 9 = 15 ==> 1+5 = 6
2+6+5+3 = 16 ==> 1+6 = 7
.....

This is identical to your answer since 10^n mod 9 is always 1 regardless of n.