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