Theorem nnoni

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

	Ref	Expression
Hypothesis	nnoni.1	$$⊢A\in \mathrm{\omega }$$
Assertion	nnoni	$$⊢A\in \mathrm{On}$$

Proof

Step	Hyp	Ref	Expression
1		nnoni.1	$$⊢A\in \mathrm{\omega }$$
2		nnon	$$⊢A\in \mathrm{\omega }\to A\in \mathrm{On}$$
3	1 2	ax-mp	$$⊢A\in \mathrm{On}$$