Definition df-9 9122

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 9114	. 2 class 9
2		c8 9113	. . 3 class 8
3		c1 7946	. . 3 class 1
4		caddc 7948	. . 3 class +
5	2, 3, 4	co 5957	. 2 class (8 + 1)
6	1, 5	wceq 1373	1 wff 9 = (8 + 1)

This definition is referenced by:  9re  9143  9pos  9160  9m1e8  9182  8p1e9  9197  5p4e9  9205  6p3e9  9207  7p2e9  9208  9nn  9225  8lt9  9254  8p2e10  9603  9p9e18  9617  9t9e81  9652  lgsdir2lem5  15584  2lgsoddprmlem3d  15662