Theorem 2z

Description: 2 is an integer. (Contributed by NM, 10-May-2004)

	Ref	Expression
Assertion	2z	⊢ 2 ∈ ℤ

Proof

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