lean_workbook_plus_1080

Proved

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

Why is $\binom{9}{4}=\boxed{126}$ ?

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_1080 : Nat.choose 9 4 = 126   :=  by sorry

Source