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Metamath Proof Explorer

Theorem 1nn0

Description: 1 is a nonnegative integer. (Contributed by Raph Levien, 10-Dec-2002)

Ref Expression
Assertion 1nn0 1 ∈ ℕ0

Proof

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