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Metamath Proof Explorer
Theorem 3z
Description: 3 is an integer. (Contributed by David A. Wheeler, 8-Dec-2018)
|
|
Ref |
Expression |
|
Assertion |
3z |
|- 3 e. ZZ |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
3nn |
|- 3 e. NN |
| 2 |
1
|
nnzi |
|- 3 e. ZZ |