Teery

42857 × 1 to ×6, the result will never escape those 6 digits:
1, 4, 2, 8, 5, 7
Only the order keeps rotating, like the digits are spinning in a circle.
But once you multiply by ×7—
142857 × 7 = 999999
Completing a full circle, instantly "returns to one," all turning into 9.
Why is this so magical?
Because 1 ÷ 7 = 0.142857142857…
This is a 6-digit infinite repeating decimal.
And 2 ÷ 7, 3 ÷ 7 … 6 ÷ 7,
are actually still this sequence of digits,
just starting from different positions.
So:
×1 to ×6 essentially involve shifting the starting point, viewing the same cycle;
×7 completes the full circl