Metamath Proof Explorer

Theorem 12nn0

Description: 12 is a nonnegative integer. (Contributed by Umit Teoman Dogan, 10-Jun-2026)

Ref Expression
Assertion 12nn0 
|- ; 1 2 e. NN0

Proof

Step Hyp Ref Expression
1 1nn0 
 |-  1 e. NN0
2 2nn0 
 |-  2 e. NN0
3 1 2 deccl 
 |-  ; 1 2 e. NN0