Theorem 9nn0

Description: 9 is a nonnegative integer. (Contributed by Mario Carneiro, 19-Apr-2015)

	Ref	Expression
Assertion	9nn0	⊢ 9 ∈ ℕ0

Proof

Step	Hyp	Ref	Expression
1		9nn	⊢ 9 ∈ ℕ
2	1	nnnn0i	⊢ 9 ∈ ℕ0