[Math] what is the symbol generally used for whole numbers

Question

For subjecting to whole numbers, what symbol should I use? it must be valid for using anywhere from school to college. The symbol should be known and well proper to be understood easily by a school student.

Answer 1

You can use $\mathbb{Z}$ for the integers, i.e. the set of numbers $\{\cdots, -3, -2 ,-1, 0, 1, 2, 3, \cdots\}$.

Or you can use $\mathbb{N}$ for the cardinal numbers, also called the counting numbers $\{1, 2, 3, \cdots\}$. Sometimes $0$ is included in $\mathbb{N}$ as well.