Description: Increasing an integer by 2 results in an integer. (Contributed by Alexander van der Vekens, 16-Sep-2018)
Ref | Expression | ||
---|---|---|---|
Assertion | zadd2cl | |- ( N e. ZZ -> ( N + 2 ) e. ZZ ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id | |- ( N e. ZZ -> N e. ZZ ) |
|
2 | 2z | |- 2 e. ZZ |
|
3 | 2 | a1i | |- ( N e. ZZ -> 2 e. ZZ ) |
4 | 1 3 | zaddcld | |- ( N e. ZZ -> ( N + 2 ) e. ZZ ) |