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 circle, carries over all, transforming into 999999.

This is the most classic "Number Cycle."

142857 is the embodiment of 1/7.
Multiplying by 1–6 is a "shifting game,"
Multiplying by 7 is the "Nine Nine Return to One."