Elementary arithmetic identity #21022

Proved

WorkbookCorrected.plus_21022

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

arithmeticcorrectedelementaryworkbook

The elementary natural-number / rational identity

1 + 4 + 9 + 16 + 25 + 36 + 49 + 64 + 81 + 100 = 10 * 21 * 11 / 6

holds by direct arithmetic evaluation.

Formalization Note: This corrects Lean-Workbook record lean_workbook_plus_21022, 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_21022 (Apache-2.0).

Preamble

import Mathlib.Tactic.NormNum

Formal statement

theorem WorkbookCorrected.plus_21022 : 1 + 4 + 9 + 16 + 25 + 36 + 49 + 64 + 81 + 100 = 10 * 21 * 11 / 6 := by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook; record lean_workbook_plus_21022; Apache-2.0; corrects Open node 01adfd83-1a81-4c92-aab5-cf2ef9002a10

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