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Metamath Proof Explorer

Theorem 4nn0

Description: 4 is a nonnegative integer. (Contributed by Mario Carneiro, 18-Feb-2014)

Ref Expression
Assertion 4nn0 4 ∈ ℕ0

Proof

Step Hyp Ref Expression
1 4nn ⊢ 4 ∈ ℕ
2 1 nnnn0i ⊢ 4 ∈ ℕ0