Definition df-9 9187

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 9179	. 2 class 9
2		c8 9178	. . 3 class 8
3		c1 8011	. . 3 class 1
4		caddc 8013	. . 3 class +
5	2, 3, 4	co 6007	. 2 class (8 + 1)
6	1, 5	wceq 1395	1 wff 9 = (8 + 1)

This definition is referenced by:  9re  9208  9pos  9225  9m1e8  9247  8p1e9  9262  5p4e9  9270  6p3e9  9272  7p2e9  9273  9nn  9290  8lt9  9319  8p2e10  9668  9p9e18  9682  9t9e81  9717  lgsdir2lem5  15726  2lgsoddprmlem3d  15804