Prove2Me

Elementary arithmetic identity #54661

Proved
WorkbookCorrected.plus_54661

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

arithmeticcorrectedelementaryworkbook

The elementary natural-number / rational identity

123+4+5+6+7+8−9=144∧123−4−5+6+7+8+9=144123 + 4 + 5 + 6 + 7 + 8 - 9 = 144 ∧ 123 - 4 - 5 + 6 + 7 + 8 + 9 = 144

holds by direct arithmetic evaluation.

Formalization Note: This corrects Lean-Workbook record lean_workbook_plus_54661, 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_54661 (Apache-2.0).

Preamble
import Mathlib.Tactic.NormNum
Formal statement
theorem WorkbookCorrected.plus_54661 : (123 + 4 + 5 + 6 + 7 + 8 - 9 = 144) ∧ (123 - 4 - 5 + 6 + 7 + 8 + 9 = 144) := by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook; record lean_workbook_plus_54661; Apache-2.0; corrects Open node b9501ede-dd46-485f-b52c-3a8560bb2e1e

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