Definition df-9 9208

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 9200	. 2 class 9
2		c8 9199	. . 3 class 8
3		c1 8032	. . 3 class 1
4		caddc 8034	. . 3 class +
5	2, 3, 4	co 6017	. 2 class (8 + 1)
6	1, 5	wceq 1397	1 wff 9 = (8 + 1)

This definition is referenced by:  9re  9229  9pos  9246  9m1e8  9268  8p1e9  9283  5p4e9  9291  6p3e9  9293  7p2e9  9294  9nn  9311  8lt9  9340  8p2e10  9689  9p9e18  9703  9t9e81  9738  lgsdir2lem5  15760  2lgsoddprmlem3d  15838