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Metamath Proof Explorer

Theorem 3on

Description: Ordinal 3 is an ordinal number. (Contributed by Mario Carneiro, 5-Jan-2016)

		Ref	Expression
	Assertion	3on	$⊢ 3_{𝑜} \in On$

Step	Hyp	Ref	Expression
1		df-3o	$⊢ 3_{𝑜} = suc 2_{𝑜}$
2		2on	$⊢ 2_{𝑜} \in On$
3	2	onsuci	$⊢ suc 2_{𝑜} \in On$
4	1 3	eqeltri	$⊢ 3_{𝑜} \in On$