Theorem 9p2e11

Description: 9 + 2 = 11. (Contributed by Mario Carneiro, 19-Apr-2015) (Revised by AV, 6-Sep-2021)

	Ref	Expression
Assertion	9p2e11	⊢ ( 9 + 2 ) = ; 1 1

Proof

Step	Hyp	Ref	Expression
1		9nn0	⊢ 9 ∈ ℕ0
2		1nn0	⊢ 1 ∈ ℕ0
3		0nn0	⊢ 0 ∈ ℕ0
4		df-2	⊢ 2 = ( 1 + 1 )
5		1e0p1	⊢ 1 = ( 0 + 1 )
6		9p1e10	⊢ ( 9 + 1 ) = ; 1 0
7	1 2 3 4 5 6	6p5lem	⊢ ( 9 + 2 ) = ; 1 1