Definition df-9 9176

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

Assertion

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

Detailed syntax breakdown of Definition df-9

Step	Hyp	Ref	Expression
1		c9 9168	. 2 class 9
2		c8 9167	. . 3 class 8
3		c1 8000	. . 3 class 1
4		caddc 8002	. . 3 class +
5	2, 3, 4	co 6001	. 2 class ( 8 + 1 )
6	1, 5	wceq 1395	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  9197  9pos  9214  9m1e8  9236  8p1e9  9251  5p4e9  9259  6p3e9  9261  7p2e9  9262  9nn  9279  8lt9  9308  8p2e10  9657  9p9e18  9671  9t9e81  9706  lgsdir2lem5  15711  2lgsoddprmlem3d  15789