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Metamath Proof Explorer

Definition df-2

Description: Define the number 2. (Contributed by NM, 27-May-1999)

		Ref	Expression
	Assertion	df-2	$⊢ 2 = 1 + 1$

Step	Hyp	Ref	Expression
0		c2	$class 2$
1		c1	$class 1$
2		caddc	$class +$
3	1 1 2	co	$class (1 + 1)$
4	0 3	wceq	$wff 2 = 1 + 1$