Metamath Proof Explorer


Theorem 7p5e12

Description: 7 + 5 = 12. (Contributed by Mario Carneiro, 19-Apr-2015)

Ref Expression
Assertion 7p5e12 ( 7 + 5 ) = 1 2

Proof

Step Hyp Ref Expression
1 7nn0 7 ∈ ℕ0
2 4nn0 4 ∈ ℕ0
3 1nn0 1 ∈ ℕ0
4 df-5 5 = ( 4 + 1 )
5 df-2 2 = ( 1 + 1 )
6 7p4e11 ( 7 + 4 ) = 1 1
7 1 2 3 4 5 6 6p5lem ( 7 + 5 ) = 1 2