Theorem 9re

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

	Ref	Expression
Assertion	9re	$$⊢9\in ℝ$$

Proof

Step	Hyp	Ref	Expression
1		df-9	$$⊢9=8+1$$
2		8re	$$⊢8\in ℝ$$
3		1re	$$⊢1\in ℝ$$
4	2 3	readdcli	$$⊢8+1\in ℝ$$
5	1 4	eqeltri	$$⊢9\in ℝ$$