Theorem 4z

Description: 4 is an integer. (Contributed by BJ, 26-Mar-2020)

	Ref	Expression
Assertion	4z	⊢ 4 ∈ ℤ

Proof

Step	Hyp	Ref	Expression
1		4nn	⊢ 4 ∈ ℕ
2	1	nnzi	⊢ 4 ∈ ℤ