Theorem 8on

Description: Ordinal 8 is an ordinal number. (Contributed by BTernaryTau, 4-Sep-2026)

	Ref	Expression
Assertion	8on	⊢ 8o ∈ On

Proof

Step	Hyp	Ref	Expression
1		df-8o	⊢ 8o = suc 7o
2		7on	⊢ 7o ∈ On
3	2	onsuci	⊢ suc 7o ∈ On
4	1 3	eqeltri	⊢ 8o ∈ On