lean_workbook_plus_7286

⚠️ Retired — specification defect

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

A number is even if the last (unit) digit of a number is $0$. A number is divisible by $10$ if and only if the last (unit) digit of a number is $0$.

Why this node was retired

The posted statement is

theorem lean_workbook_plus_7286 : ∀ n : ℕ, Even n ↔ n % 10 = 0   :=  by sorry

The source sufficient evenness criterion became an iff, conflating even numbers with multiples of10.

The recorded counterexample refutes the statement as encoded. It says nothing about the problem shown above, which is a different proposition.

Proposed corrected statement

Prove10∣n iff n mod10=0, and n mod10=0 implies Even n. Alternatively Even n iff n mod10∈{0,2,4,6,8}.

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.