Theorem 9re

Description: The number 9 is real. (Contributed by NM, 27-May-1999)

	Ref	Expression
Assertion	9re	⊢ 9 ∈ ℝ

Proof

Step	Hyp	Ref	Expression
1		df-9	⊢ 9 = ( 8 + 1 )
2		8re	⊢ 8 ∈ ℝ
3		1re	⊢ 1 ∈ ℝ
4	2 3	readdcli	⊢ ( 8 + 1 ) ∈ ℝ
5	1 4	eqeltri	⊢ 9 ∈ ℝ