Factorial arithmetic identity #48406

Proved

WorkbookCorrected.plus_48406

by carlok · Sep 29, 2026 · Mathlib 0df444a (Lean v4.33.1)

arithmeticcorrectedelementaryworkbook

The elementary natural-number / rational identity

15 * ((Nat.factorial 4) * (Nat.factorial 2)) = 1 * ((Nat.factorial 6))

holds by direct arithmetic evaluation.

Formalization Note: This corrects Lean-Workbook record lean_workbook_plus_48406, which omitted a compilable colon/type annotation and/or used a preamble of only Mathlib.Analysis.Complex.Basic.

Source: InternLM Lean-Workbook, record lean_workbook_plus_48406 (Apache-2.0).

Preamble

import Mathlib.Data.Nat.Factorial.Basic
import Mathlib.Data.Rat.Defs
import Mathlib.Tactic.Ring
import Mathlib.Tactic.NormNum

Formal statement

theorem WorkbookCorrected.plus_48406 : (15:ℚ) * ((Nat.factorial 4) * (Nat.factorial 2)) = (1:ℚ) * ((Nat.factorial 6)) := by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook; record lean_workbook_plus_48406; Apache-2.0; corrects Open node ac15ad0c-4755-4f72-8e7b-e229b386dfd3

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