lean_workbook_plus_78814

Proved

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

The (much) simpler way to count is $\left \lfloor \frac {999} {6} \right \rfloor - \left \lfloor \frac {99} {6} \right \rfloor = 166 - 16 = 150$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_78814 :
  Finset.card (Finset.filter (λ x => 6∣x) (Finset.Icc 1 999)) - Finset.card (Finset.filter (λ x => 6∣x) (Finset.Icc 1 99)) = 150   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook

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