lean_workbook_plus_72564

⚠️ Retired — specification defect

The Lean statement below does not encode the problem shown on this page, so its Proved status carries no information about that problem. Do not import this node or use it as a dependency.

for all odd number $u$, Prove that there exist $n$ that $u \mid 10^{n}-1$

Why this node was retired

The posted statement is

theorem lean_workbook_plus_72564 (u : ℕ) (hu : u % 2 = 1) : ∃ n : ℕ, u ∣ (10^n - 1)   :=  by sorry

No positive-exponent condition is imposed.

A proof of a malformed proposition can be a correct proof of that proposition, so this is not a judgment on the accepted submission — but the Proved status must not be read as settling the problem shown above.

Proposed corrected statement

Ask ∃ n≥1, u ∣ 10^n−1 under Nat.Coprime u 10; oddness alone is insufficient, since u=5 is a counterexample.

Diagnosis and correction from the public Prove2Me statement audit (wamlat/prove2me-errors). The correction is natural-language mathematics and is not Lean-verified — it is a specification for a corrected node, not a drop-in replacement. No corrected replacement node exists yet.