Theorem nnon

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

	Ref	Expression
Assertion	nnon	$$⊢A\in \mathrm{\omega }\to A\in \mathrm{On}$$

Proof

Step	Hyp	Ref	Expression
1		omsson	$$⊢\mathrm{\omega }\subseteq \mathrm{On}$$
2	1	sseli	$$⊢A\in \mathrm{\omega }\to A\in \mathrm{On}$$