Prove2Me

An exact arithmetic evaluation

Proved
WorkbookSource.problem_47286

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

lean-workbooksource-checked

Evaluate 20×21+202120 \times 21 + 2021 .

Source: InternLM Lean-Workbook, record lean_workbook_47286 (Apache-2.0). The complete source proposition and its explicit variable declarations are preserved.

Preamble
import Mathlib
open Real Nat
Formal statement
theorem WorkbookSource.problem_47286 (a : ℕ) : 20 * 21 + 2021 = 2441  :=  by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, record lean_workbook_47286; Apache-2.0

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