Natural numbers may be called counting numbers.
Some people begin the natural numbers with 0, corresponding to the non-negative integers 0, 1, 2...
On the other side there are people, who start with 1, corresponding to the positive integers 1, 2, 3...
There is no universal agreement about whether to include zero in the set of natural numbers.
Set of natural numbers is denoted by the letter ℕ
Set of natural numbers can be written down as:
ℕ $ = \{1,2,3,4,5,6,7,8,...\}$
If we assume that the zero is a natural number, then we have:
ℕ $ = \{0,1,2,3,4,5,6,7,8,...\}$