Theorem 5on

Description: Ordinal 5 is an ordinal number. (Contributed by BTernaryTau, 4-Sep-2026)

	Ref	Expression
Assertion	5on	Could not format assertion : No typesetting found for |- 5o e. On with typecode |-

Proof

Step	Hyp	Ref	Expression
1		df-5o	Could not format 5o = suc 4o : No typesetting found for |- 5o = suc 4o with typecode |-
2		4on	$$⊢4_{𝑜}\in \mathrm{On}$$
3	2	onsuci	$$⊢\mathrm{suc}{4}_{𝑜}\in \mathrm{On}$$
4	1 3	eqeltri	Could not format 5o e. On : No typesetting found for |- 5o e. On with typecode |-