Factorial arithmetic identity #39385
ProvedWorkbookCorrected.plus_39385arithmeticcorrectedelementaryrepairedworkbook
The elementary natural-number identity
holds by direct arithmetic evaluation.
Formalization Note: This corrects Lean-Workbook record lean_workbook_plus_39385, which omitted a compilable colon/type annotation and/or used a preamble of only Mathlib.Analysis.Complex.Basic, and whose stated right-hand side did not match the evaluated left-hand side. The repaired statement keeps the combinatorial/arithmetic left-hand side and uses the evaluated integer right-hand side (original RHS was 90).
Source: InternLM Lean-Workbook, record lean_workbook_plus_39385 (Apache-2.0).
Preamble
import Mathlib.Data.Nat.Factorial.Basic import Mathlib.Tactic.NormNum
Formal statement
theorem WorkbookCorrected.plus_39385 : (Nat.factorial 8) / ((Nat.factorial 2) * (Nat.factorial 2) * (Nat.factorial 2) * (Nat.factorial 2)) = 2520 := by sorry
Source