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Metamath Proof Explorer

Definition df-3

Description: Define the number 3. (Contributed by NM, 27-May-1999)

		Ref	Expression
	Assertion	df-3	$⊢ 3 = 2 + 1$

Step	Hyp	Ref	Expression
0		c3	$class 3$
1		c2	$class 2$
2		caddc	$class +$
3		c1	$class 1$
4	1 3 2	co	$class (2 + 1)$
5	0 4	wceq	$wff 3 = 2 + 1$