Whole Numbers (Z)

Whole numbers are all integers (positive or negative)

1. $+1 \in Z$
2. $-1 \in Z$
3. $-1 \notin N$

Translation:

1. Positive number 1 in set Z (whole numbers)
2. Negative number 1 in set Z (whole numbers)
3. Number -1 not in set N (natural numbers)