Definition df-9 9320

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 9312	. 2 class 9
2		c8 9311	. . 3 class 8
3		c1 8144	. . 3 class 1
4		caddc 8146	. . 3 class +
5	2, 3, 4	co 6058	. 2 class (8 + 1)
6	1, 5	wceq 1398	1 wff 9 = (8 + 1)

This definition is referenced by:  9re  9341  9pos  9358  9m1e8  9380  8p1e9  9395  5p4e9  9403  6p3e9  9405  7p2e9  9406  9nn  9423  8lt9  9452  8p2e10  9806  9p9e18  9820  9t9e81  9855  lgsdir2lem5  16031  2lgsoddprmlem3d  16109