intro n₁ (ih : ∀ y, n₁ ≃ y → n₁ * m ≃ y * m) n₂
ℕ : Type
inst✝⁵ : Core ℕ
inst✝⁴ : Induction ℕ
inst✝³ : Addition ℕ
inst✝² : Sign ℕ
inst✝¹ : Order ℕ
inst✝ : Multiplication ℕ
n₁ n₂ m : ℕ
⊢ ∀ (m_1 : ℕ), (∀ (y : ℕ), m_1 ≃ y → m_1 * m ≃ y * m) → ∀ (y : ℕ), step m_1 ≃ y → step m_1 * m ≃ y * m
ℕ : Type
inst✝⁵ : Core ℕ
inst✝⁴ : Induction ℕ
inst✝³ : Addition ℕ
inst✝² : Sign ℕ
inst✝¹ : Order ℕ
inst✝ : Multiplication ℕ
n₁✝ n₂✝ m n₁ : ℕ
ih : ∀ (y : ℕ), n₁ ≃ y → n₁ * m ≃ y * m
n₂ : ℕ
⊢ step n₁ ≃ n₂ → step n₁ * m ≃ n₂ * m