Metamath Proof Explorer

Theorem 3nn0

Description: 3 is a nonnegative integer. (Contributed by Mario Carneiro, 18-Feb-2014)

Ref Expression
Assertion 3nn0 
|- 3 e. NN0

Proof

Step Hyp Ref Expression
1 3nn 
 |-  3 e. NN
2 1 nnnn0i 
 |-  3 e. NN0