Theorem plusgndx

Description: Index value of the df-plusg slot. (Contributed by Mario Carneiro, 14-Aug-2015) (New usage is discouraged.)

	Ref	Expression
Assertion	plusgndx	⊢ ( +g ‘ ndx ) = 2

Proof

Step	Hyp	Ref	Expression
1		df-plusg	⊢ +g = Slot 2
2		2nn	⊢ 2 ∈ ℕ
3	1 2	ndxarg	⊢ ( +g ‘ ndx ) = 2