lean_workbook_plus_80083

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

What is $20\times 20 - 19\times 19$ ?

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_80083 : 20 * 20 - 19 * 19 = 39   :=  by sorry

Source