Definition df-9

Description: Define the number 9. (Contributed by NM, 27-May-1999)

	Ref	Expression
Assertion	df-9	|- 9 = ( 8 + 1 )

Detailed syntax breakdown

Step	Hyp	Ref	Expression
0		c9	|- 9
1		c8	|- 8
2		caddc	|- +
3		c1	|- 1
4	1 3 2	co	|- ( 8 + 1 )
5	0 4	wceq	|- 9 = ( 8 + 1 )