Definition df-9 9251

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 9243	. 2 class 9
2		c8 9242	. . 3 class 8
3		c1 8076	. . 3 class 1
4		caddc 8078	. . 3 class +
5	2, 3, 4	co 6028	. 2 class (8 + 1)
6	1, 5	wceq 1398	1 wff 9 = (8 + 1)

This definition is referenced by:  9re  9272  9pos  9289  9m1e8  9311  8p1e9  9326  5p4e9  9334  6p3e9  9336  7p2e9  9337  9nn  9354  8lt9  9383  8p2e10  9734  9p9e18  9748  9t9e81  9783  lgsdir2lem5  15834  2lgsoddprmlem3d  15912