lean_workbook_plus_20728

Proved

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

Thinking through this, weighing anything up to $\left\lfloor\frac{3^k}{2}\right\rfloor$ takes $k$ weights. $\lceil\log_3(2\cdot2009)\rceil=\boxed{8}$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_20728 (k : ℕ) (h₁ : 0 < k) (h₂ : 2 * 2009 ≤ 3 ^ k) : k >= 8   :=  by sorry

Source