Metamath Proof Explorer


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