The last digit of a power of twelve

Proved

WorkbookSource.problem_40641

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

lean-workbooksource-checked

The last decimal digit of $12^{100}$ is $6$ :

12^{100}\equiv6\pmod{10}.

Source: InternLM Lean-Workbook, record lean_workbook_40641 (Apache-2.0). The complete source proposition and explicit variable declarations are preserved.

Preamble

import Mathlib
open Real Nat

Formal statement

theorem WorkbookSource.problem_40641 : 12 ^ 100 ≡ 6 [ZMOD 10]  :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_40641; Apache-2.0

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