Metamath Proof Explorer


Theorem 2z

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

Ref Expression
Assertion 2z
|- 2 e. ZZ

Proof

Step Hyp Ref Expression
1 2nn
 |-  2 e. NN
2 1 nnzi
 |-  2 e. ZZ