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Metamath Proof Explorer

Theorem 2nn0

Description: 2 is a nonnegative integer. (Contributed by Raph Levien, 10-Dec-2002)

Ref Expression
Assertion 2nn0 
|- 2 e. NN0

Proof

Step Hyp Ref Expression
1 2nn 
 |-  2 e. NN
2 1 nnnn0i 
 |-  2 e. NN0