Definition df-9 9325

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 9317	. 2 class 9
2		c8 9316	. . 3 class 8
3		c1 8146	. . 3 class 1
4		caddc 8148	. . 3 class +
5	2, 3, 4	co 6060	. 2 class ( 8 + 1 )
6	1, 5	wceq 1398	1 wff 9 = ( 8 + 1 )

This definition is referenced by:  9re  9346  9pos  9363  9m1e8  9385  8p1e9  9400  5p4e9  9408  6p3e9  9410  7p2e9  9411  9nn  9428  8lt9  9457  8p2e10  9811  9p9e18  9825  9t9e81  9860  lgsdir2lem5  16037  2lgsoddprmlem3d  16115