Definition df-9 8900

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 8892	. 2 class 9
2		c8 8891	. . 3 class 8
3		c1 7734	. . 3 class 1
4		caddc 7736	. . 3 class +
5	2, 3, 4	co 5825	. 2 class (8 + 1)
6	1, 5	wceq 1335	1 wff 9 = (8 + 1)

This definition is referenced by:  9re  8921  9pos  8938  9m1e8  8960  8p1e9  8974  5p4e9  8982  6p3e9  8984  7p2e9  8985  9nn  9002  8lt9  9031  8p2e10  9375  9p9e18  9389  9t9e81  9424