I'm sorry, I'm an ordinary Japanese, not good at English and math.
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And I found these things.
6 digits include 142857.
3 digits in front + 3 digits in the back = 999 (red cells) stand up a lot.
The starting point of 142857 changes, but flows from left to right and returns from right to left. The sort order of 142857 does not change.
Not only 142857, other types of 6-digit repeating decimal places are often found. And the front 3 digits + back 3 digits of this recurring decimal number = 999
front 2 digits + middle 2 digits + back 2 digits = 99 or 198 (99 times 2) can often be found.
The first number with repeated decimal places is 360 Division 49 (7 times 7).
These things are known in the mathematical world?