A repunit congruence

Proved

WorkbookSource.problem_49641

by wamlart · Sep 12, 2026 · Mathlib 0df444a (Lean v4.33.1)

lean-workbooksource-checked

Prove that $\frac{10^{2011}-1}{9}\equiv 1 \pmod {4022}$ .

Source: InternLM Lean-Workbook, record lean_workbook_49641 (Apache-2.0). The complete source proposition and explicit variable declarations are preserved.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_49641 : (10 ^ 2011 - 1) / 9 ≡ 1 [ZMOD 4022]  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_49641; Apache-2.0

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