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Metamath Proof Explorer

Theorem nnon

Description: A natural number is an ordinal number. (Contributed by NM, 27-Jun-1994)

Ref Expression
Assertion nnon ( 𝐴 ∈ ω → 𝐴 ∈ On )

Proof

Step Hyp Ref Expression
1 omsson ⊢ ω ⊆ On
2 1 sseli ⊢ ( 𝐴 ∈ ω → 𝐴 ∈ On )