Theorem nnoni

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

	Ref	Expression
Hypothesis	nnoni.1	⊢ 𝐴 ∈ ω
Assertion	nnoni	⊢ 𝐴 ∈ On

Proof

Step	Hyp	Ref	Expression
1		nnoni.1	⊢ 𝐴 ∈ ω
2		nnon	⊢ ( 𝐴 ∈ ω → 𝐴 ∈ On )
3	1 2	ax-mp	⊢ 𝐴 ∈ On