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Metamath Proof Explorer

Theorem nncn

Description: A positive integer is a complex number. (Contributed by NM, 18-Aug-1999)

Ref Expression
Assertion nncn 
|- ( A e. NN -> A e. CC )

Proof

Step Hyp Ref Expression
1 nnsscn 
 |-  NN C_ CC
2 1 sseli 
 |-  ( A e. NN -> A e. CC )