Definition df-9 9048

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 9040	. 2 class 9
2		c8 9039	. . 3 class 8
3		c1 7873	. . 3 class 1
4		caddc 7875	. . 3 class +
5	2, 3, 4	co 5918	. 2 class ( 8 + 1 )
6	1, 5	wceq 1364	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  9069  9pos  9086  9m1e8  9108  8p1e9  9122  5p4e9  9130  6p3e9  9132  7p2e9  9133  9nn  9150  8lt9  9179  8p2e10  9527  9p9e18  9541  9t9e81  9576  lgsdir2lem5  15148  2lgsoddprmlem3d  15198