Metamath Proof Explorer


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