lean_workbook_plus_67799

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

Prove that $2^{21} \equiv 1 \pmod 7$ without a calculator.

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_67799 : 2 ^ 21 ≡ 1 [ZMOD 7]   :=  by sorry

Source