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 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 9nn0 | |- 9 e. NN0 |
|
2 | 1nn0 | |- 1 e. NN0 |
|
3 | 0nn0 | |- 0 e. NN0 |
|
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 |