Definition df-9 9349

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 9341	. 2 class 9
2		c8 9340	. . 3 class 8
3		c1 8170	. . 3 class 1
4		caddc 8172	. . 3 class +
5	2, 3, 4	co 6075	. 2 class (8 + 1)
6	1, 5	wceq 1402	1 wff 9 = (8 + 1)

This definition is referenced by:  9re  9370  9pos  9387  9m1e8  9409  8p1e9  9424  5p4e9  9432  6p3e9  9434  7p2e9  9435  9nn  9452  8lt9  9481  8p2e10  9835  9p9e18  9849  9t9e81  9884  lgsdir2lem5  16065  2lgsoddprmlem3d  16143